326 SUMMARY OF CURRENT RESEARCHES RELATING TO 



The author also suggests that hydrocyanic acid, which is present in 

 many germinating seeds, may be of importance in facilitating the 

 proteolysis of the reserve-materials of the seed. 



Cane-Sugar in the Reserve Food-Stuffs of Phanerogams.* — E. 

 Bourquelot, as a result of the chemical examination of the roots, rhizomes, 

 bulbs, seeds, and other deposits of reserve food in a number of plants, in 

 almost all of which he is able to demonstrate the presence of cane- 

 sugar, comes to the conclusion that this carbohydrate is a sort of prin- 

 ciple necessary to nutritive changes in all phanerogamic plants. The 

 occasional failure to demonstrate its presence is probably due, not to 

 its absence, but to the fact that the action of invertine, by means of 

 which it was recognised, was masked by the existence of another 

 principle. 



Conversion of Carbohydrate in the Germination of the Date.f — 

 J. Griiss finds the hydrolysation products of an enzyme action on the 

 reserve-cellulose in the date endosperm to be mannose, galactose, dex- 

 trose, and fructose. This carbohydrate nourishment is supplied to 

 the embryo in the form of cane-sugar which constitutes 44 p.c. of the 

 dry weight of the cotyledonary sucker. There is no conversion into 

 transitory starch on its passage to the shoot. The author demonstrates 

 a striking agreement in the action of the enzyme of date-endosperm and 

 of malt-diastase respectively. Both convert a-mannan first into mannin 

 and finally into mannose, and galactan into galactin and finally galactose, 

 and both act on starch, though malt-diastase is the more energetic agent. 

 Finally, both work the same corrosive action on reserve-cellulose. 



General. 



Quantitative Study of Variation in the Bracts, Rays, and Disk- 

 florets of Species of Aster.} — G. H. Shull has studied the varia- 

 tion in the organs mentioned in four species of Aster from Yellow 

 Springs, Ohio. After describing his method of work he gives an ex- 

 haustive account of his results, which are illustrated by numerous dia- 

 grams and tables. A close correlation was found between bracts and 

 rays, which is attributed to the fact that the rays are axillary to the 

 bracts ; and the degree of imbrication of the bracts was observed to 

 bear a relation to the number of empty bracts. Curves and "constants" 

 were determined ; constants for several individuals of A. jpuniceus grow- 

 ing in identical surroundings showed great variation in the variability 

 " constants." The number of bracts, rays, and disk-florets (in A. pre- 

 nanthoides) was found to decrease continuously from the beginning to 

 the ©nd of the flowering season. The author finds that the suggestion 

 that statistical methods will prove valuable in taxonomic work is not 

 sustained by his results ; and also emphasises the importance of an 

 intelligent selection of material for work on variation. 



Passage from a Bisexual to a Unisexual Condition by Uni- 

 lateral Parasitic Castration. § — A. Giard reviews some recent work by 

 Meehan on the action of certain fungi which inhabiting the root of 

 species of Vcmonia caused remarkable changes in the general habit of 



* Compt. Rend., cxxxiv. (1902) pp. 71S-20. 

 t liot. Zeit., xx. (1902) pp. 30-44. 

 t Amer. Nat., xxxvi. (1902) pp. 111-52 (40 figs.). 

 § Compt. Rend., cxxxiv. (1902) pp. 14G-9. 



