402 



BOTANY. 



which multiply by fission, and eventually unite into a con- 

 tinuous tissue (in reality a false tissue), the endosperm (en, 

 Fig. 297, B). In this mass of endosperm cells several near 

 the micropylar end grow larger than the surrounding ones, 

 and become filled with granular protoplasm. These are the 



corpuscula of Brown, the 

 archeyonia of Sachs, or 

 the secondary embryo sacs 

 of Henfrey (cp, cp, Fig. 

 297, B}. In some cases 

 they are placed singly at 

 short distances from each 

 other, while in others they 

 are clustered together 

 (1 and 2, Fig. 298). Each 

 corpusculum is at first a 

 single cell, but when fully 

 developed it consists of an 

 elongated cell, the germ- 

 cell proper, and, in many 

 cases at least, one or more 

 neck-cells, the whole sunk- 

 en deeply into the sub- 

 Fig. 298 -1. Three corpnecula. cp, of Juni- stance of the endosperm. 

 erus rrminiuiiia, close together, and seen in a . , . , , , r ., 



ngitudinal section of the ovule ; rf, the first lllC neck IS formed by the 

 suspcnsor cells of two fertilized corpuscnla , , a e .c 



at the tipper end of the corpuscula are shown Cutting Off 01 a portion OI 



ISK the original cell of the cor- 



endosperm in enlarged embryo sac ; <?', portion . - 



of endosperm broken up : cp. three corpus- f Orm a Vertical TOW 



cula, from the lower ends of which the BUS 



fore, v. grow 



3 X 100 ; 4 X 



v. grow ; p, pollen tube. 1 and 2 X 

 ; 50.-After Hofmeieter. 



? it remains single, while in 



cleus,",*;/:, of the ovule, shown in outline ; , others it divides SO as to 



and 



l j in others a four- or even 

 eight - celled transverse 

 plane (see Fig. 298, 1) ; the latter arrangement has been 

 termed a rosette. 



511. If we now review the structure of the ovule its ho- 

 mologies can be readily made out. The ovule itself plainly 

 corresponds to the macrosporangium of the higher Pterido- 

 phytes, and the embryo sac is to be regarded as the homo- 



