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Professor F. E. Nipher gave an account of the Geissler and Crookes tubes and the radiant phenomena exhibited by each when used in connection with a high-tension electrical current of rapid alternation, and detailed the recent discoveries of Professor Röntgen, showing that certain of the rays so generated are capable of affecting the sensitized photographic plate through objects opaque to luminous rays. Attention was also called to the experiments of Herz and Lodge with discharges of very high tension alternating currents, which showed that by the latter certain invisible rays are produced, which, like the Röntgen rays, are capable of passing through opaque bodies, such as pitch, but differing in their refrangibility by such media.
March 2d.—Mr. F. W. Duenckel presented a comparison of the records of the United States Meteorological Observatory, located on the Government building in the city, with the record for the Forest Park station, showing that the daily minimum averaged decidedly lower at the Forest Park station than in the city, while the wind averaged decidedly higher for the city station.
Professor E. E. Engler spoke on the summation of certain series of numbers.-WILLIAM TRELEASE, Recording Secretary.
The Journal of Comparative Neurology, which is now entering upon its sixth volume, has its editorial facilities considerably enlarged by the addition to the staff of Dr. Oliver S. Strong, of Columbia College. Professor C. L. Herrick continues as Editor in-Chief. The Managing Editor for 1896, is C. Judson Herrick, to whom business communications should be addressed at Denison University, Granville, O. Editorial communications may be sent to either of the three editors.
THE PROBABLE INFLUENCE OF DISTURBED NUTRITION ON THE EVOLUTION OF THE VEGETA
TIVE PHASE OF THE SPOROPHYTE.
BY GEO. F. ATKINSON.
In this paper the discussion of the influence of nutrition, applies chiefly to that source of nutrition in plant organs provided with chlorophyll, and presupposes, in general, that the ordinary physiological processes, other than the one which is termed carbon assimilation, are normal. In all such plants some development of this vegetative part of the plant must take place before spore production, or fruiting, of a kind which represents a real increase at the time, can be accomplished. Some apparent, but not real, exceptions to this might be noted. In germination of the spores of Oedogonium, frequently spore production takes place without the development of any such vegetative part of the plant, but there is no real increase of the plant substance. This kind of spore production is only a means, perhaps, to tide over some condition unfavorable for the elaboration of the vegetative phase of the plant, which is present at the time and place. In Coleochæte, germination of the
oospore results in the formation of a cellular mass, which Cornell University.
is larger than the oospore, breaks the enclosing wall, and the cells escape as a number of zoospores in place of one. But in this oospore are the stored products of carbon assimilation of the parent chlorophyll phase of the plant, and this case only differs from that of the Bryophyta, in that the sporophyte becomes separated, with stored products, from the gametophyte, before the differentiation of the spores.
In the higher plants many cases of bulbs, corms, tubers, etc., might be cited to show that the development of the sporophylls, and even fruit, might take place without the accompaniment of chylorophyll bearing organs. But here also the bulbs, corms, etc., represent, in the stored products of carbon assimilation, the preceeding green leaves. In certain ferns, as Osmunda cinnamomea, the sporophyll, which is completely differentiated from the vegetative leaf, appears first in the spring, and could mature its spores without the aid of the vegetative leaves of that season, but the green leaves of the previous season formed the necessary carbohydrates, which are stored in the rhizome and rudimentary leaves during the winter and in fact the sporophylls and sporangia are partly developed at the close of the previous season.
We might say, then, that in general, all spore production in plants, which themselves assimilate carbon dioxide, is necessarily preceeded by a greater or lesser development of chlorophyll bearing organs. This may appear to be a too well known axiom for even the brief discussion here given, but it is necessary in view of what is to come to have this axiom well in mind. Chlorophyll bearing organs, or tissues, then, as compared with sporogenous organs or tissues, are, in point of time within the life cyle, primary, while the latter are secondary. This proposition should not be regarded as opposed to the primary evolution of the sporophylls as compared with the foliar organs of the sporophyte. It applies only to a comparatively limited extent of time; to the usual cycle between the vegetative and fruiting phases; to the ontogenetic, not to the phylogenetic, development. It applies with equal force to plants in which either the gametophyte or the sporophyte forms the chlorophyll bearing organ.
There is a strong tendency in nature to an economy in the distribution of the food supply between foliar, and sporophyllary, organs; between the vegetative and fruit products of the plant. This is well seen in the varying sizes of plants having varying amounts of food supply, where with limited food supply small plants have few and small leaves accompanied by a limited out-put of fruit (other conditions are considered normal); while with increasing amounts of food, other things being equal, each of these plant products is increased, though not in the same ratio. With high feeding the vegetative increase shows a higher ratio than the fruiting. The food may be so abnormally abundant as to cause an abnormally abundant vegetative growth, accompanied in some cases with rudimentary fruit, or in others with the entire suppression of the fruit. In some rare cases it may be accompanied by the transformation of the sporophyllary organs to vegetative ones.
These facts teach that the fruit product, or sporophyllary development of plants is very sensitive to food supply, requiring a certain amount of food for perfection in even small quantities, increasing with additional food supply up to a given point, when it decreases again to zero; or in rare cases the sporophyllary organ may be transformed to a vegetative one, 80 antagonistic has the ratio between the vegetative and sporophyllary organs become because of the abnormally favorable conditions for vegetative growth. In addition to the sensitiveness which the fruit organs exhibit to varying amounts of food derived from the soil, they are very sensitive to disturbances in the supply of carbohydrates as a result of carbon assimilation in the vegetative organs, especially of a kind which partly or completely cuts off that supply. This is well seen in the diminished crops as a result of injury to the leaves at critical periods from insects or fungi, or as result of unfavorable meteorological conditions.
When the nutritive supply of the carbohydrates is suddenly disturbed by certain kinds and amounts of injury to the foliage leaves, or by pruning severely, thus cutting off a large number of forming or developed leaves, certain parts of the plant, either simple or in a rudimentary condition of development, have the function of carbon assimilation forced upon them to save the plant from destruction and to provide for the development of the fruiting organs.
As is well known, latent buds, which have been in a dormant condition, may be, for years, are frequently in such cases stimulated to development and form leafy shoots. It is a very common occurrence as a result of severe pruning or of injury to the ordinary leaves for young flower axes, or buds, to develop leafy shoots with other flower buds in the new leaf axils. There is a tendency here to force the vegetative function upon the young flower axes, and if this influence is felt before the specialized character of the floral organs has been developed from the cells at the apex of the axis, the development of these organs will be deferred, while these cells assume the form and function of vegetative organs. This is a matter, perhaps, of common observation as a result of severe pruning, and in some plants can be very easily demonstrated by trial. But it serves well to show the influence of disturbed nutrition on other or dormant parts of the plant when the function of the existing vegetative leaves is arrested. That function is forced from the ordinary and well developed organs upon undeveloped or rudimentary ones, which readily under this influence adapt themselves to continue this important office. This must not be regarded as an attempt to explain the development of adventitious or supernumerary buds, etc., or latent buds, in all cases, into leaf branches. Local stimuli, and a number of other causes at times, call forth leafy shoots from these. Nevertheless, in view of what has been said above, the following proposition might be formulated. Nutrition disturbed, and the development of the fruit product of the plant being threatened, by the loss of carbon-assimilating organs, the function of the latter may be taken up by some other part of the plant, either rudimentary or undifferentiated, their development into said organs being a direct result of that disturbance.
In the cases dealt with above, the function is either transferred to latent vegetative organs, or to undifferentiated tissues. It is, therefore, simply and easily comprehended.
Observations have been made, however, which tend to show that in