84 Prof. J. Reynolds Green and Mr. H. Jackson. [Mar. 22, 



the end of this time the uninjured epidermis .had produced such a change 

 in the globulin that the solution gave a vivid reaction for tryptophane on 

 addition of a little chlorine water. The contents of the other tube were 

 unchanged. The presence of trypsin in the cotyledonary epidermis was 

 consequently proved. An extract of the cotyledons gave the same results. 

 Taking these experiments in conjunction with Mr. Biffen's observations, 

 there can be little or no doubt that the special cells alluded to secrete 

 the trypsin. 



These observations throw a light upon certain phenomena already alluded 

 to, which were first recorded by Van Tieghem,* and subsequently corrobo- 

 rated by one of us.f Van Tieghem dissected the embryos out of seeds of 

 Eicinus and exposed the endosperms on damp moss for some weeks to 

 a temperature of 25 to 30° C. After several days of this exposure he found 

 them growing considerably, and at the end of a month they had doubled 

 their dimensions. The change was caused by the enlargement and partial 

 separation of the constituent cells. In the interior of the cells he found the 

 aleurone grains to be gradually dissolving, and the oily matter to be slowly 

 diminishing. In the confirmatory experiments made by one of us the 

 changes were found to be much more rapid when pieces of the cotyledons 

 were left in contact with the endosperms than when the embryo was 

 entirely removed. No satisfactory explanation of these phenomena was 

 forthcoming at the time that they were observed, but the discovery that the 

 tryptic enzyme is secreted by the cotyledons affords one. That a very slow 

 germination takes place in the complete absence of the cotyledons may be 

 explained by a small exudation of the enzyme from the latter before their 

 removal or by the endosperm-cells themselves secreting a small quantity of it 

 when the growth of the protoplasm is resumed during the early stages. The 

 diffusion of the trypsin from the cotyledons into the tissue of the endosperm 

 is exactly paralleled by the diffusion of diastase from the scutellum of the 

 barley grain, described by Brown and Morris.J 



Conclusions. 



The germination of the seed of Eicinus is shown by the experiments now 

 recorded to be associated with a remarkable activity of the cells of the 

 endosperm, which spring into renewed life and set up a very complex 



* Van Tieghem, "Sur la Digestion d' Albumen," 'Comptes Kendus,' vol. 84 (1877), 

 p. 578. 



t Loc. cit., p. 389. 



% Brown and Morris, " On the Germination of some of the Graminese," ' Journ. Chem- 

 Soc.,' vol. 57 (1890), p. 495. 



