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SPECIAL ARTICLES

LONG-LIVED CELLS OF THE REDWOOD THE principal features of long-lived cells in the massive stems of cacti have recently been described by the senior author.1 Medullary cells of the tree cactus (Carnegiea) were seen to remain alive for periods well over a century and the results of the examination of elements of all ages indicate active enlargement during the second half of the century.

Another cactus, the melon cactus or bisnaga (Ferocactus), which has an ovoid-cylindrical trunk was found to include similar medullary cells of great age which, however, ceased to grow after the first decade. The development of the outer cortex as a layer several inches in thickness is of such character as to demonstrate that the cortical cells have a similar period of enlargement and survival.

In all of these cells the carbohydrate components, pentosans and hexoses progressively decrease with age. The fatty substances, or lipins and nitrogenous substances, change least.

Transformation of sugars to wall-material with consequent thickening is apparent in Carnegiea and in the medulla of Ferocactus; crystals of salts accumulate in all cases. It was notable, however, that in the cortex of Ferocactus the disappearance of the carbohydrates extends even to the walls, which are thinner at a hundred yards than at ten, suggesting the liquefaction and removal of pentosans. It seems probable that the only consumption or use of the lipins from these cells is of that which may be in the walls and cytoplasm, and that these substances in the nuclei are but little affected.

That ray cells may attain an age of many years in the whitish sap wood of tree trunks is implied in the

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writings of many authors. We can not find any definite statement of living cells in heart wood, although Strasburger's account of starch in trunks of the red beech 125 layers from the surface suggests that these cells might be alive.2 The negative assertion that "only the outer layer of the wood composed of the more recently-formed annual rings thus contain living cells and constitutes the splint-wood" made in the 14th German edition of Strasburger's text-book of botany and found on p. 158 of the 5th English revision as translated by Lang in 1921 may be taken as a correct presentation of present knowledge of this matter.

Certain features of behavior of the trunks of the California Redwood uncovered by our study of the hydrostatics of this tree led us to examine the parenchymatous cells of the trunks. There are two different types of living cells in newly-formed secondary xylem of Sequoia sempervirens: wood-parenchyma cells that stand in vertical files scattered among the tracheids, and ray-parenchyma cells. As in most other woody stems, the wood-parenchyma and rayparenchyma cells of the alburnum or whitish sapwood are living and densely packed with starch.

The change from alburnum to duramen (heartwood), macroscopically recognizable in Sequoia by a brownish-red coloration of the duramen, is accompanied by a disappearance of starch and protoplasts from all wood-parenchyma cells and the formation of an orange-colored resin that completely or partially fills the lumen of the wood-parenchyma cells. For this reason wood-parenchyma cells are often called resin cells. The transition from alburnum to duramen is also accompanied by a disappearance of starch from the ray-parenchyma cells but this disappearance of the starch is not always followed by death and disintegration of the protoplasts. These living ray cells of the duramen have a thin layer of cytoplasm next the wall, a conspicuous nucleus, and a large central vacuole. The ray cells may remain unchanged for a long time and we have observed ray-parenchyma 70 layers deep in the heartwood with clearly defined protoplasts and apparently normal nuclei. As the sapwood in such trees included 21-23 layers these cells were about a century old. Cells of older annual increments in these stems also appeared to be living but this could not be determined with certainty since the granular nature of the cell contents obscured the nuclei. Some trees have ray-parenchyma cells that show a granular cytoplasm and small droplets of resin shortly after the transition from duramen to

2 Strasburger, E. "Ueber den Bau und Verrichtungen d. Leitungbahnen in den Pflanzen.” Pp. 274

275. 1891.

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alburnum; still others have the same behavior in ray-parenchyma and wood-parenchyma and both elements in the outermost ring of heartwood contain resin only.

The reasons for this marked variation in the behavior of ray-parenchyma cells are as yet unknown. The age of the tree does not appear to be a factor, for we have found both conditions in young and in old trees. Neither is there any sharp correlation with the environment. Trees high on the dry flanks of hills or deep in the canyons of this vicinity may have living ray cells deep in the duramen.

That these cells should survive during the pronounced changes in chemical constitution of the wood, altered composition of the sap and lessened oxygen supply is a remarkable occurrence. The nuclei undergo but little change and a superficial examination suggests consumption of the carbohydrates. The well-known abrupt diminution of starch in the rays occurs in the redwood at the stage of transition from sap to heartwood. The ratio of length of life of these cells to that of their growing period is the highest known. Full size is reached almost at once— within a few days-life may continue for a century or four thousand times the duration of the growing period. In Carnegiea medullary cells continue to enlarge for a century; in Ferocactus life continues for a period ten or twelve times the growing period which extends over a decade.

It is notable that the known long-lived cells of plants are all of the simple parenchyma type as in contrast with the highly specialized long-lived cells of the brain and heart of vertebrates.

The medullary cells of Carnegiea which grow for a century, as might be expected, retain their embryonic character. Those of the medulla and cortex of Ferocactus do not. The long-lived cells of the redwood lose their capacity for division at an early stage and play no direct part in the formation of calluses, or other regenerative action so marked in the redwood. In what way the existence of these numerous strips of living cells in the heartwood, which may reach an age of more than a century, affect the pressures and movements of liquids and gases in this tree is yet to be determined. The facts presented seem to constitute the first announcement of living cells in heartwood, as well as an extension of knowledge of the occurrence and behavior of long-lived cells.

D. T. MACDOUGAL GILBERT M. SMITH

LABORATORY FOR PLANT PHYSIOLOGY,

CARNEGIE INSTITUTION OF WASHINGTON

AND

DEPARTMENT OF BOTANY,

STANFORD UNIVERSITY

GLUCOSE AS AN ANTAGONIST

FOR some years the senior author has been engaged in the study of the habits and means of control of the onion root maggot (Hylemyia antiqua Meig.). Experiments have included extensive investigation of the chemotropic responses of the flies to various substances. Cane molasses has always proved a very satisfactory attractant and NaCN has long been known and used as an effective insect poison. In consequence, a mixture composed of 4 ounce of NaCN, 1 pint of molasses, and 1 gallon of water, was included among the various poisoned baits it was desired to test.

In the summer of 1925, Mr. K. Stewart, working on the same problem, found that the NaCN-molasses bait gave very satisfactory results, ranking first of all the materials tried in the average daily catch of Diptera. These records were obtained by the use of wire fly-traps of the Minnesota type placed in the onion fields on the College farm, with the various poison baits in glass dishes under the traps.

The NaCN-molasses combination, as one of the most promising of the mixtures under trial, was selected by the senior author for further experimentation in 1926. It continued to give very satisfactory results so far as the catch of flies was concerned, but some doubt was experienced as to the extent to which this mixture was acting as a killing agent. Accordingly, cage experiments were started indoors in order to settle this point. It was found that while the NaCN combination was even more attractive to the flies than molasses and water alone, its toxicity was practically nil. Upon uncorking a bottle of the mixture which had been well shaken and then allowed to stand for several days, a distinct odor of ammonia was noticed, while that of HCN could no longer be detected. Moistened litmus paper gave the alkaline color reaction when held near the mouth of the bottle. Apparently, the CN group had been decomposed, giving rise to ammonia, the evolution of which gas no doubt explains the enhanced attractiveness to the flies of the poisoned bait over that of a simple molasseswater solution.

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Glucose solutions to which NaCN was added were found to give essentially the same results as did the molasses bait, but to a more pronounced degree. Further confirmation of the hypothesis respecting the origin of the ammonia is afforded by the results obtained with a mixture of cane-sugar solution (of the same specific gravity as that of the molasses used) and NaCN in the proportions of 4 ounce of the latter to 1% gallons of the former. When this mixture was used in cage experiments it was found that the HCN given off usually was sufficient to kill most of the flies without their having the opportunity to start feeding. Sucrose, having no free carbonyl group, would of course not undergo the cyanhydrin reaction.

In connection with the above, it is interesting to recall that Rasputin, the Russian monk who dominated the court of the late Czar, is reputed to have used glucose as a protection against sundry attempts upon his life by means of poison. Such results as have been described would suggest that this precautionary measure was well taken, in the case of NaCN at least. In addition, the findings of Heinekamp1 respecting the resistance of various types of fowl to strychnine, furnish evidence that here also glucose, or its polymer glycogen, may have a rôle as antagonist in the case of the alkaloids as well as in that of the less complex poisons.

DEPARTMENT OF ENTOMOLOGY, MACDONALD COLLEGE, MCGILL UNIVERSITY

ALEX. D. BAKER W. A. DELONG

GEOCHRONOLOGY AS BASED ON SOLAR RADIATION

In this journal of 1920 was mentioned a part of my plan for an investigation of certain laminated clays in North America.

During a previous visit in this country in 1891, I had, at several places, observed laminated clays similar to analogous late glacial melting sediments in Sweden, which I had found, after long-continued investigations, to represent the annual deposition from the melting water along the border of the retreating ice-edge.

By help of a certain graphic method for the comparison of the sharply marked annual layers or varves, I had succeeded in identifying such varves from one point to another and ultimately worked out a systematic plan for the elaboration of a continuous time scale. This was in the main carried out in 1905-06 on the basis of field measurements 1 Heinekamp, W. J. R., "The Resistance of Fowls to Strychnine." Jour. Lab. and Clin. Med. 11: 209-214 (1925).

made, for a considerable part, by a great number of able young assistants. During the following years this standard line was completed at many places. I thus succeeded, step by step, in tracing the recession of the ice border and the immediately following transgression of the clay-varves over one region after the other, until the whole line from southernmost Sweden to its central parts had been controlled.

As was to be expected, the lowest and oldest clayvarves were found to be deposited in the southernmost part of the land, while the great ice-sheet still covered the rest. By following the clay transgression step by step, the whole staircase-like series was gradually built up, forming a continuous and exact time scale for the last ice-recession across Sweden up to a certain year when a great ice-dammed lake in central north Sweden was drained off, and a thick annual varve was deposited, which has been chosen as representing the very end of the late Glacial Epoch

proper.

For many years I tried in vain to find out any means of determining the length of this Postglacial Epoch, until one of my most successful assistants, R. Lidén, discovered, in the northern parts of Sweden, measurable annual varves which represent that epoch.

Of varves from this epoch, I measured in one section at the Indal River somewhat over 3,000, but it was along the Angerman River that Lidén quite independently succeeded in finding and working out practically the whole of the Postglacial varve succession by a careful and painstaking combination of a long series of sections, showing the total length of the Postglacial Epoch to be about 8,700 years.

What made his work especially important is that there seems to be no other place in the world, not even in Sweden, where there is any possibility of finding such a continuous varves series for the whole of the Postglacial Epoch.

By noting the position of the bottom varves, the ice-recession in Sweden has been determined in detail at certainly more than 1,500 different localities, while sections down to the very bottom varve elsewhereexcepting in Finland-have but rarely determined the front margin of the lowest varve.

Thus, along the Connecticut Valley, according to Antevs' exceedingly interesting and comprehensive varve measurements, the bottom of the clay layers was so seldom exposed that the bottom varve, which marks the stage of the ice-recession, could only be determined at one point along the whole of the southern four fifths of the measured line of ice-recession. Even the remaining fifth part of the line, which is north of a gap in the section not represented by clay deposits, the bottom varve was located at only five points.

Though in this region it is not yet possible to know exactly the rate of ice-recession, the numerous measurements of long varve series have afforded valuable material for detailed teleconnections with the time scale in Sweden and a thorough and very satisfactory verification with respect to the thickness variation of "the varves of some otherwise uncontrolled parts of the Swedish time scale.

Furthermore, though it has not been possible, even to such an admirable varve tracer as Dr. Antevs, to find a continuous varve series through the late glacial part of the time scale in Canada, this is, happily enough, of less importance since the extended teleconEnections with the already minutely controlled Swedish time scale afford an equally good but much more convenient and time-saving method.

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Thus it is neither necessary nor advisable to use uncertain estimates or perhaps quite erroneous assumptions for filling out gaps between actually measured varve series, if the whole sum really is to be trustworthy.

nd a Furthermore, considering that the initiative, the Porganization and method of the investigation are totally of Swedish origin, and, as it seems, it is only in Sweden that the time scale can be continued all the way up to our own age, it may be fully justified to name this chronologic standard line the Swedish Time scale, even where it is identified and completed by parallel measurements in other countries.

The main purpose of an exact international chronology must be the reference of different kinds of events everywhere to one and the same time standard. The necessary condition for the introduction of such a time scale was, of course, the possibility of identification, even at great distances, of synchronous varve variations. This condition seems now to be realized.

Thus, almost all of the varve series measured in 1920 by the little Swedish expedition to North America have been with certainty identified with corresponding series of the time scale in Sweden, as illustrated by some examples representing a few thousands of years, published in the Geografiska Annaler, Stockholm, 1926. Quite lately the author has also succeeded in identifying a series of nearly 600 varves, carefully measured in Argentina by one of my former pupils, Dr. Carl Caldenius.2 Also a description of E. Norin's varve measurements in

1 G. De Geer, "On the Solar Curve, as Dating the Ice Age, the New York Moraine and Niagara Falls through the Swedish Time Scale." Data, 9. Geogr. Ann., Stockholm, Vol. 8 (1926), pp. 253-284, Pls. 1-3 (varve diagrams and map).

2 G. De Geer, "Late Glacial Clay Varves in Argentina, measured by Dr. Carl Caldenius, dated by Means of the Solar Curve through the Swedish Time Scale." Data, 1. Ibidem, Vol. 9 (1927), pp. 1-8, Pl. 1 (varve diagrams).

northwestern Himalaya, carried out and identified by him in 1925 and 1926, will soon appear in the same journal.

Considering that the distances between Sweden and the other regions are no less than 6,000-14,000 km., the similarity of more than 80 per cent. of the whole varve number between the identified varve series is very astonishing but quite convincing with respect to the long and uniform succession of characteristic varve variations, which, naturally enough, have not been possible to connect in more than one single way. It is especially noteworthy that this similarity continues century after century, thus, as it seems, putting it beyond every doubt that only a real identity is able to explain such a considerable sum of similarities.

Here it must also be emphasized that it was first after many totally vain attempts that the striking correspondence was discovered, and then was at once found to be continuous over practically the whole of the varve series.

A close study already made of the published diagrams will soon show that a mere accident here must be totally shut out. This remarkable coincidence of such rapid variations at such considerable distances, caused by simultaneous ice-melting, seems not to be explicable in any other way than by variations in the amount of heat from the sun. Thus in reality, we have to do with nothing less than a gigantic, selfregistering thermograph, showing the variations in

the radiation from the sun.

With respect to the physics of the sun, it is of interest that there exists an observed biennial variation as well as the annual one, this latter being indicated by the connection of the varve variation of the two hemispheres, so that the north and south summers, with their closely corresponding varves, point to a natural thermal year. Still it is undetermined whether that year begins with the one hemisphere or the other.

It may be of interest for the elucidation of this question to include also the southern part of the Cordilleran observations which are analogous to the renowned measurement of the solar radiation which, for two decades, have been executed on the sunny heights in the far West of the United States.

Whatever may be the astronomic cause of the annual solar variation, it seems likely that its beginning and end probably are to be found somewhere between the north and south summer, or not far from the equinoxes. When this has been fully stated, our annual means of temperature ought to be calculated for the natural thermal year, which ought to give much more characteristic results than the means of the arbitrary fiscal year.

Though it may be granted that the varve variation as to its dominating features all over the earth is a function of the sun radiation, at the same time it is still more or less influenced by local factors, such as the bottom topography at different localities together with changes in the direction of the melting rivers, the varying composition of the morainic material from which the clay is washed out, and other circumstances. By parallel measurements at different localities, many such deviations from the true solar curve will probably be eliminated, but meanwhile it is not advisable to transcribe the varve thicknesses in figures intended for smoothing calculations.

Yet a really convincing graphic connection already observed makes it possible for the first time to introduce in an exact way the time factor into a great number of geophysical investigations hitherto beyond our reach. Thus, to mention a few examples, the possibility of mapping and dating synchronous land ice borders over great areas in different regions of the earth enables us to take up, with respect to the physics of large ice bodies, a rational study of ice movement, of ice extension, and of its recession as a function of melting as well as of fracturing.

In the papers quoted, some hints are given concerning the use of time determinations for a closer geophysical study of other processes, of inorganic as well as of organic nature, such as the evolution of our actual climate and the erosion along our rivers as well as our lake and sea shores. In these papers was especially mentioned the magnificent example of Niagara Canyon, the age of which has now been geochronologically dated by means of good varve connections. Thanks to the excellent measurements by American and Canadian geologists, we have here a prime example of the amount of river erosion under certain conditions during a non-determined space of time.

Here may be mentioned furthermore the new possibilities of studying, step by step, how the ice recession was followed by the formation of soil and vegetable mould and the immigration of the whole flora and fauna within the former great ice deserts, which afford unique possibilities of supplying certain branches of geology with exact geophysic studies. GERARD DE GEER

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geographic isolation. A species on a given host may remain limited to that host over long periods of time. During the lapse of time modification of the fungus occurs resulting in distinct varieties. Further changes lead to specific, even generic, differentiation. It thus happens that distinct but related forms are found on one host species. The evolution of these occurred during the tenancy of this phylum on this host. The occurrence of b complexes of numerous related species on a given host g family is very striking. No significant deductions from geographic distribution are evident; indeed, the most striking fact is the relative evenness in which the vari-ion ous genera and species are distributed over the Meliola world. Apparently evolutionary tendencies have operated in diverse areas in much or quite the same way. The course of evolution appears to have been from the non-hyphopodiate, 8-spored forms with persistent asci and spores of variable septation to hyphopodiate, 24spored forms with evanescent asci and spores of definite septation, leading to the establishment of six genera within the group. It appears that these genera are of i polyphyletic origin, each having arisen several, perhaps. many times, from different ancestral stocks.

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Some studies on the composition of vegetative and i fruiting plants: E. J. KRAUS (introduced by John M. Coulter). Accumulating evidence on many types of plants shows that there is often a marked tendency for the gradual accumulation in the proportion of carbohy drates and carbohydrate-like compounds in excess of the nitrogenous constituents as the fruiting stage approaches. In some instances the differences in composition seem more specifically related to the relative solubility of the nitrogenous and carbohydrate constituents than to changes in actual proportions of these substances, the it more fruitful plants containing a larger proportion of t relatively insoluble substances. The general trend of the results is the same whatever the external environmental factors concerned in prolonging or shortening the vege tative period.

Progress with work on disease-resistant plants: L. R. Pr JONES.

The dynamics of plant growth to soil conditions, with special reference to oxygen and carbon dioxide: BURTON E. LIVINGSTON (introduced by W. A. Noyes).

The quantum efficiency of the photochemical decompo sition of anhydrous formic acid: WESLEY NORMAN HERR and W. ALBERT NOYES, JR. (introduced by Julius Stieglitz). The number of quanta required to decompose one molecule of anhydrous formic acid in the liquid state has been determined. The light intensities were measured by means of a thermocouple and the transmitted light subtracted from the incident light to obtain the amount of light absorbed. The source of light used was a quartz mercury arc lamp. The amount of decomposi tion is determined by gently boiling the liquid until the decomposition products are removed and then by measur

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