184 BOTANICAL GAZETTE [SEPTEMBER 
the surface of all protoplasm; (2) physical considerations lead to belief in a 
) plasma 
s; (4) the membrane is of high viscosity, probably a gel, which readily 
reverts to a liquid sol state; (5) it is capable of ready adjustment to changes 
in contour and area; (6) protoplasm in most cases forms a membrane almost 
instantly on the surface; exceptions are due to extreme liquidity; (7) the 
living membrane is rather delimited from the inner plasma, but it cannot be 
isolated from it; (8) the degenerated, coagulated plasma membrane can some- 
times be isolated, being then of finer consistency, elastic, and exceedingly 
tough; (9) the nucleus and vacuoles also possess protoplasmic membranes 
resembling the-outer plasma membrane; (10) the thickness of the membrane 
is probably about 0.1 
Protoplasm, when dissected i in water, in most cases is immiscible in it. 
When it is miscible, it is caused by extreme liquidity or disintegration. The 
immiscivity is possibly due to the colloidal and chemical nature of the proto- 
plasm. The absorption and retention of water by protoplasm are essentially 
inhibition processes—Ww. CROCKER. 
Food storage in cotyledons.—DuccArR” has found that removal of the 
cotyledons of the pea seedling at an early stage of growth causes a much slower 
development of the plant, but their removal after the food is largely withdrawn 
causes no reduction in growth rate. Removal of the endosperm of the corn 
has far less effect. Glycocoll and sodium nucleinate in water culture partially 
substitute for the loss of the cotyledons. Asparaginate and alanin depress 
e growth with cotyledons removed. The author is to run experiments in 
sterile conditions to further test the possibility of organic materials substituting 
for the cotyledons —WM. CROCKER. : 
Disease resistance.—McLEAN*™ concludes that Szinkum mandarin is 
resistant to citrus canker because its stomata are of such shape as to exclude 
liquid water and thus stop the entrance of the motile bacterium that produces 
the canker. The Florida seedling grapefruit which is susceptible to this 
_ disease has stomata of about the same size, but they are of such shape as to 
permit the accumulation of liquid water in the stomata and allow the entrance 
of the bacterium.—Wa. Crocker. 
 Duccar, B. M., The nutrition value of food reserve in cotyledons. Ann. Mo. 
Bot. Gard. 7:291-298. 1920 
at MCLEAN, F. T., A ee of the structure of the stomata of two pet of es 
in relation to the dines canker. Bull. Torr. Bot. Club 48:101—106. 
