IS Stnpcs und Fujii, The nutritive relations <>l' 1 1 » »_■ Burrounding tissuea etc 



already enumerated, we find thal the following brief acconnl holds 

 • Kl for all the cases we observed. 



The egg cell, which acts as a point of attraction for the Eood 

 siutl's. is supplied with soluble Eood passing in through the 

 endosperm. While it is young and growth is rapid apparently the 

 snpply does qoI very mach exceed the demaud and no food is 

 deposited in solid tonn. Later however the balance is reached 

 and so soon as the snpply becomes greater than the demanda of 

 the growing egg depositioo in solid or semisolid form begins round 

 it. In the case of starch, dcposition a/?/v//,s takes place firsl in the 

 eells of the endosperm at the base of the archegonia. In differenl 

 groups the relative time of deposition and the State of development 

 of the egg may vary greatly, for example in the Cycads and Ginkgo 

 hoth starch and protein substauce are largely deposited in the 

 endosperm before the growth of the unfertilized egg is completed, 

 but in Pinus dcposition is extremely slighl in the endosperm even 

 after the enibryo has reached a considerable size. 



In all cases, at some time or times in the course of its 

 development we found both starch and protein substance deposited 

 in the egg cell itself. The protein substance is early deposited in 

 large grains in the egg of Cycads and Ginkgo, and some grains 

 are still present even after the formation of the proembryo. Starch 

 on the other band is much more vacillating in the egg, and has 

 the appearance of "transitory starch", being present in very fine 

 grains which are largely of the nature of amylodextrine. Both 

 starch and protein substance are deposited first in the perifery of 

 the egg cell, but later they are found scattered throughout the 

 cytoplasm, probably being carried round by an internal Streaming. 

 The formation of transitory starch grains along the perifery of the 

 protoplast of the egg is at times very conspieuous, and is certainly 

 the result of the conversion of diosmosable sugars into uon- 

 diosrnosable starch immediately after the entry of the former into 

 the egg cell. Similarly the entering proteid is deposited in grains 

 near the perifery. By this means the concentration of the soluble 

 food in the egg cell is kept constantly below that of the surrounding 

 cells, which ensures a continual transfer into the egg. and at the 

 sanie time prevents a too great concentration of osmotic substances 

 in the egg cell itself. 



If then the process of the entry of food is such as we have indi- 

 cated, what is the chief fnwtion of the jacket Injcr which is so very well 

 characterised, particulaily in the lower Gymnosperms? As we have 

 already inentioned in the Cycads and (itnkgo the snpply of food 

 in the early stages is greatly in excess of the demands of the 

 growing egg : so that much is deposited in solid form, tili, in fact, 

 the endosperm cells are packed with it. Once the food in the 

 surrounding cells is laid down in solid form, the egg cell is 

 practically cut off from it nnless there is some means of rendering 

 it soluble, or transmitting it into easily diosmosable substances; 

 and it is here that we think the jacket cells play an important 

 part. Though the presence of a large quantity of stored food in 



