70 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Physiology. 
Food-reserve m Cotyledons. — B. M. Duggar {Ann. Missour. Botan. 
Card., 1920, 7 , 291-98, 1 pi., 2 figs., 2 tabs.). The author has studied 
the nutritive value of the food -reserve in cotyledons and in endosperm. 
In the first experiment twenty-four pairs of seedlings of field-peas were 
grown in culture-solution, and the cotyledons of one of each pair of 
seedlings weie removed on each day for twenty-four days. For a period 
of seven days this removal caused a marke l but diminishing depression 
in the rate of growth of the seedling as compared with that of the 
control. Further experiments, somewhat modified, show that the 
cotyledons are practically exhausted in ten days ; removal after that 
period produced little effect upon growth. The removal of the scutella 
and endosperm from corn-seedlings produced similar, but far less marked, 
results. In subsequent experiments attempts were made to substitute 
organic nitrogenous nutrients, such as glycocoll, alanin, sodium 
asparaginate and sodium nucleinate, for the loss of the cotyledons, but 
with unsuccessful results. The failure appears to be due to (1) need 
for a combination of amino acids, or (2) the difficulty and slowness of 
penetration of organic substances, or (8) the absence of a vitamine that 
may be found in the cotyledons. All plants like beans and peas which 
have fleshy cotyledons show a similar depression of growth when these 
cotyledons are removed, and the influence of this depression is perceptible 
throughout the entire period of growth of the plant. S. G-. 
Synthesis of Carbohydrates in Plants.— E. Baly, I. Heilbron 
and W. Barker {Journ. Chem. Soc., 1921, 119 - 20 , 1025-35). A 
study of the synthesis of formaldehyde and carbohydrates from carbon 
dioxide and water. It is now proved that an aqueous solution of 00 2 
gives formaldehyde when exposed to light of very short wave-length 
(A = 200 fx/x). When the solution is further exposed to light of wave- 
length 290 fx/x, the formaldehyde is polymerized to reducing sugars. 
This photosynthesis can be induced in ordinary white light by the use 
of malachite-green, methyl-orange and other coloured basic substances 
as catalysts. Under certain conditions of screened lighting an equi- 
librium is set up between the relative amounts of sugar, formaldehyde 
and C0 2 , but in unscreened light the equilibrium lies far over to the 
side of the C0 2 ; in the presence of a photocatalyst, capable of function- 
ing in both stages of the reaction, the equilibrium is shifted entirely 
over to the side of the reducing sugar. Chlorophyll appears to be an 
ideal photocatalvst of this description, and thus the formation of carbo- 
hydrates in the growing leaf without the free existence of formaldehyde 
is explained. S. G. 
General. 
Inbreeding and Crossbreeding in Crepis. — J. L. Collins {Univ. 
Californ. Pub. Agric. Sc. //., 6 . 1920, 205-16, 3 pis.). The results of 
inbreeding and crossbreeding in Crepis capillaris show that the con- 
ditions induced by inbreeding this naturally cross-fertilized plant 
strongly resemble those produced by inbreeding of maize. The third 
and fourth generations exhibit the maximum reduction. The F x genera- 
tion of plants produced by crossing inbred strains with non-inbred 
