416 SUMMARY OF CURRENT RESEARCHES RELATING TO 



position of carbon dioxide, 20 per cent., and, under specially favourable 

 circumstances, as mucb as 40 per cent., of the entire solar energy is 

 utilized by the chlorophyll, the proportion thus used up being very 

 much larger than has been assumed by Pfeffer and Pringsheini. 



Sphserocrystals.* — A. Hansen has examined the structure of 

 crystals in a number of plants. Those found in the cells of several 

 species of Euphorbia agree in general with the ordinary form, and 

 consist of calcium phosphate ; as also do those of MesemhryantJiemum 

 and of Marattia cicutcefoUa and Angiopteris evecta. Those of Gocculus 

 laurifolius and of Capsella, on the other hand, do not consist of any 

 phosphate, but are apparently organic in their nature. 



The author asserts that sphserocrystals do not grow, either by 

 apposition or in any other way. They appear in the cell-contents in 

 the form of drops, which gradually harden into solid bodies. They 

 are invested by a pellicle ; and their striking stratification does not 

 result from their mode of growth, but from a differentiation during 

 hardening. 



The conclusions of the author were confirmed by observing the 

 behaviour of artificial sphserocrystals made of calcium phosphate and 

 calcium carbonate. 



Sphserocrystals of Paspalum elegans.f — According to J. Borodin, 

 if sections of the leaf of Paspalum elegans are moistened with alcohol, 

 and the latter allowed to evaporate under the cover-glass, peculiar 

 yellow sphserocrystals make their appearance, which shine brightly 

 in polarized light. They are easily soluble in hot, less easily in cold 

 water, rapidly in dilute hydrochloric acid, and especially in weak 

 potash-lye, colouring it an intense yellow. When carefully warmed, 

 they melt into homogeneous intensely yellow, strongly but not doubly 

 refractive balls, still soluble in water. The substance which affords 

 these sphserocrystals is very peculiarly distributed in the plant. It 

 occurs only in the lamina of the leaves, the leaf-sheaths and stems 

 being quite free from it. It is especially abundant in the apical part 

 of the leaf. The distribution of potassium nitrate is exactly the 

 reverse. 



Although these properties resemble to a certain extent those of 

 leucin in the dahlia, yet careful experiments show that the substance 

 which yields these sphserocrystals is not leucin. But under special 

 circumstances leucin is found in the leaf of Paspalum elegans. 



Calcium Oxalate in Bark.J — From observations made on the 

 deposits of calcium oxalate in the bark of a considerable number of 

 trees, S. Eauner is led to adopt the ordinary view that this substance 

 is an excretory product, and not a reserve food-material. He found 

 that they did not disappear from the bark as the new shoots were put 

 out, but were constantly present at all times of the year. 



* SB. Phys.-Med. Gesell. Wurzburg, 1883, pp. 20-2. 



t Arbeit. St. Petersb. Naturf. Gesell., xiii. (1883) pp. 47-60 (Kussian). See 

 Bot. Centralbl., xvii. (1884) p. 102. 



X Arbeit. St. Petersb. Naturf. Gesell., xiii. (1883) pp. 24-33 (Russian). See 

 Bot. Centralbl., xvii. (1884) p. 101. 



