403 



BOTANT. 



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

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

 Fig. 397, 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 



corpiiscula of Brown, the 

 a7'chegonia of Sachs, or 

 the secondary embryo sacs 

 of Henfrey {cp, cp, Pig. 

 397, 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. 398). Each 

 corpusculum is at first a 

 single cell, but when fully 

 developed it consists of an 

 elongated cell, the germ- 

 cell proper, and, in ma-ny 

 cases at least, one or more 

 neck-cells, the whole sunk- 

 en deeply into the sub- 

 Fig. 298—1. Three corpuecula. f7), oi Jurti- stance of the endospcrm. 

 perus commwm^ close together, and seen in a r„- i • <. t i i i 



Tongiiudinal section of theovnle ; ei, the first ihc neck IS formed by the 

 suspensor cells of two fertilized corpnscula — ,,. £e £ „ j.* „ j: 



at the upper end of the corpascula are shown Cutting OH: 01 a portion 01 

 the neck cells ; », the lower end of the pollen ,r „,.;„;„„i „„ii „f j-l,„ „„,, 

 tube. 2. A similar section taken a little later ; tne Ollgmai Ceil 01 tne COr- 

 «>, », the suspensors, or pro-embryos; e, e, e, nnafnliiTn • in omno nnspu 

 cells of the endosperm. 3. Lowe? end of BUS- P^^®'^'^^'^'"' ^^ ®"™® ^^^^ 

 pensor, with enibryo.«6, beginning to develop, it remains single, while in 

 4, Longitudinal section ol the body or "nu- . .*^ ' 



cleuB,"**, of the ovule, shown in outline; e, others it divides SO aS tO 

 endosperm in enlarged embryo sac ; c', portion „ ,• i -i 



of endosperm broken up; ep. three corpus- lorm a Vertical rOW, and 

 cula, from the lower ends of which the suspen- • ,^ « 



sors, V. grow ; p, pollen tube. 1 and 2 X 300 ; m Others a lour- or even 



B X 100 ; 4 X 65-.-After Hofmeister. ^-^-^^ _ ^^^^^^ tranSVerse 



plane (see Pig. 398, 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- 



