T. S. COBBOLD ON THK EMP.RYOr.OGY OF ACHnrENES PICTA. 23 



Hofmeister has probably done more than anyone else, but the 

 observations of Sanderson, especially in regard to the embryology of 

 Hippuris vulgaris, are particularly valuable. To Sanderson and 

 Unger we are indebted for a complete account of the formation of 

 the endosperm in Hippuris, and by their records it appears that the 

 embryo-sac becomes filled with a multicellular matrix before the act 

 of fertilisation actually takes place. What is ordinarily described 

 as the suspensor, was called by Sanderson the " filamentous 

 prolongation " of the embryo, which it is important to observe is not 

 developed within the tubular or upper end of the impregnated germ- 

 cell or vesicle until after the formation of those parent cells of the 

 embryo which form the globular bud suspended by the filament. 

 Into the details of endospermal formation there is no need to enter, 

 but what I want to point to is the extent to which Sanderson's 

 observations go to support the views of Sachs and others who hold 

 that the suspensor (whether it be a long and much divided fila- 

 ment, or only a solitary cell) is a development essentially different 

 from the embryo itself. On the acceptance or rejection of certain 

 supposed analogies, or homologously identical parts, as the case 

 may be, rests the hypothesis of the existence of an alternation of 

 generation in phanerogams, strictly comparable to that which has 

 long been recognised as occurring in Cryptogamia. Whether this 

 hypothesis be admitted or not, the proofs of essential unity of 

 the sexual process throughout the vegetable series of organisms, 

 remain unaffected. Although the question of the source of 

 nutriment to the growing embryo and germinating seed — whether 

 this nourishment be derived from the endosperm, or from the peri- 

 sperm (which sometimes supplies its place, functionally), or from 

 the seed-lobes of the embryo itself, which in exalbuminous plants 

 has, as it were, stolen the food from the displaced or absorbed 

 endosperm in an early stage of formation — although the question, 

 which was partly raised by Mr. Martinelli's recent paper, is 

 undoubtedly, a very interesting one, I cannot now enter ujDon it, 

 my object being to receive the verdict of the botanical members of 

 the Club as to whether there is, or is not, any good ground for re- 

 garding the two separate embryonal processes of Cryptogams and 

 Phanerogams as fundamentally one and the same. The interest of 

 the question at issue does not stop here, for if this view, in the form 

 that it is advocated by Sachs, be rendered untenable, I think that 

 the ordinary views that are entertained in respect of the adult 



