504 



SCIENCE. 



[X. S. Vol. XXI. Xo. .53.). 



(It has been impossible to obtain an ab- 

 stract of this paper.) 



Further Studies on Hie Starch Grain 

 (third paper) : Dr. Henry Kraemer, 

 PhiLndelphia College of Pharmacy. 

 The author called attention to the altera- 

 ation in the compound starch grains of the 

 seeds of Theohroma Cacao on the applica- 

 tion of heat, producing masses resembling 

 the natural starch grains of corn, wheat, 

 barley, rye and potato, in size and shape, 

 and showing in some cases even a con- 

 centric or exeentrie lamellated structure. 



In the micro-polariscopic examination of 

 reserve starch grains of different origin, it 

 was observed that in using a red and green 

 selenite plate the yellow and blue areas did 

 not occupy the same relative position in 

 all of the grains, so that in the same field 

 with the analyzer at a given position two 

 kinds of grains were observed which were 

 the complement of each other. Three ex- 

 planations are suggested as accounting for 

 this difference in the polarizing effects of 

 different starch grains of the same origin : 



1. It may be due to a difference in the 

 shape and structure of the individual 

 grains. 



2. It may be due to a difference in com- 

 position of the different parts of the same 

 grain. 



3. Or it may be that there are two dis- 

 tinct kinds of grains. This view seems to 

 offer the most plausible explanation for 

 this phenomenon. 



Regarding the Cause of Sap Pressure and 

 Floiv in the Maple: Dr. K. M. Wiegand, 

 Cornell University. 



Kesearches by various investigators have 

 shown that the seat of pressure in the 

 maple, during the sugar season, is not in 

 the root, but in the aerial parts, principally 

 in the trunk. It seems to be induced by 

 temperature acting as a stimulus. When 



this rises past 2°-4° C. pressure results, 

 but a freezing of the tissue is by no means 

 necessary. The author has attempted, by 

 the aid of mathematical calculation and the 

 employment of other evidence at hand, to 

 compare critically the various theories. It 

 becomes evident that neither gas, water 

 nor wood expansion, nor any combination 

 cf these, can account for the phenomen(n. 

 Neither can the freezing theory. We have 

 left the theory that pressure is due to the 

 living cells, which agrees well with the 

 facts. Only the pith rays seem to be in the 

 proper position in the wood to allow the 

 production of pressure. Pressure in this 

 case could be due only to the unequal per- 

 meabilit}', in opposite directions, of the 

 membrane at the two ends of the cell. This, 

 quite likely, is caused by the penetration 

 of the morning temperature. Water would 

 tend to pass from the inner layers to the 

 outer ; and the solute, sugar, would be ex- 

 creted as a neeessaiy factor in the produc- 

 tion of pressure. 



Notes on Some Species of Agavicus {Psal- 

 liota) : Professor G. F. Atkinson, Cor- 

 nell University. 



Photographs of eight or ten species were 

 shown to illustrate characters and show 

 some points in the development and forma- 

 tion of the veil and annulus. Photomicro- 

 graphs of the spores of nearly all the species 

 in the United States were also shown, and 

 special attention was called to the value of 

 these in a study of different species. 



Nuclear Changes in Germinating Seeds: 

 Professor Carrie M. Derick, McGill 

 University. 



In this paper a brief summary was given 

 of the results of part of an investigation 

 into the cytological conditions connected 

 with anabiosis which had been begun under 

 the direction of Professor Strasburger, at 

 Bonn, and continued at IMcGill University. 



