Stopes and Fujii, The nutritive relations of the surrounding tissues etc. 19 



the eudosperui tissues does not necessarily mean that no soluble 

 food passes through these cells to the egg cell, yet when cells 

 become packed with stored food their chief function ceases to be 

 that of passage cells, and the stored food itself is certainly not 

 available in that form. So far as we can judge by the results 

 obtained by treating living material with Gujac resin, the jacket 

 cells secrete oxydase and diastase which dissolves the starch in the 

 neighbonring cells as it is reqnired by the egg. Further, we have 

 observed how the endosperrn cells surrounding the egg gradually 

 lose their starchy contents as the egg cell grows (cf. lig. 8). 

 A similar Solution and disappearance of the protein grains in the 

 endosperm also takes place and we think it is probable that 

 proteases are also secreted by the jacket cells, but as yet 

 unfortimately we have been unable to demonstrate their actual 

 presence in these cells. 



The regularity of the arrangement of the jacket cells, their 

 large nuclei and thick cytoplasm rieh in granulär contents, all 

 unite in supporting the view that they are glandulär or secretory 

 in nature, and act as go-betweens for the egg cell and the stores 

 of food in the endosperm cells. To some of the very fine well 

 marked granulär bodies present in large numbers in the jacket cells 

 we may look for the proenzymes or zymogenes. 



It is interesting to comp are this view of the jacket cells with 

 the results of some observations on Angiosperms in which the 

 antipodal cells are found to have an important part to play in the 

 passage of food to the egg cell. Westermaier's 1 ) original view 

 that the antipodals in the Ranunculaceae had an important nutritive 

 function, was followed and confirmed by Osterwalder 2 ), Goldflus 3 ), 

 Ikeda 4 ) and Lötscher 5 ) in other groups of Angiosperms. By all 

 these workers the antipodals are supposed to have the power of 

 obtaining for the egg cell and of passing on to it the food materials 

 which are present in the surrounding tissue. It is to be remembered 

 that phylogenetically the antipodals are generally supposed to represent 

 the reduced prothallium tissue; so that antipodals and jacket cells 

 are in a way homologous. The present existence and differentiation 

 of the Antipodals in some Angiosperms is due to their similar 

 physiological function performed by them, and which corresponds 

 with that of the more definitely organised jacket layer in Gymno- 

 sperms. 



When we come to the Pines we find the jacket cells less 

 strongly differentiated than in the Cycads and Ginkgo, which we 



v ) Westermaier, M., „Zur Embryologie d. Phanerog. . . . u. d. sogen. 

 Antipoden". (Nova Acta Acad. Leop. Carol. 57. 1. 1890.) 



2 ) Osterwalder, A., „ßeitr. z. Embryol. v. Aconitum Napellus". (Flora. 

 85. 1898. p. 254—292.) 



3 ) Goldi'lus, M., ..Sur la struet. et les fonet. de Tassise epithel, et d. 

 antipod. chez 1. Composces". (Journ. d. Bot. 12. 1898 and 13. 1899.) 



4 ) Ikeda, T., ,.Studies in the physiolog. funet. of antipodals in Tri/cirtis 

 hirta-'. (Bull. Coli, of Agricult. Tokyo Irap. Univ. Vol. V. 1902.) 



B ) Lötscher, P. K.. „Ueb. d. Bau u. d. Funkt, d. Antipoden in d. 

 Angiosp". (Flora. Band 94. 1905. p. 213—262.) 



2* 



