m 



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 

 archegonia 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, Pig. 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 corpnecnia; cp. of juni- stance of the endosperm. 



perus communis, clrse together, and seen in a „,i i • j. t -i j_i 



longiiudiiial section of the ovnle ; el, the ftret The neCK IS tormed by the 

 suspeneor cells of two fertilized (orpuBcnla — ,,• is j; i.- * 



at the npper end of the corpnscula are i-hown Cutting On 01 a portion 01 



lSL"%^.'l''s1iferTecrn"taTe'naM«e?at™ the Original Cell of the COr- 



^i!j?f\h^reS^^lrrT"™w'eTenk1;fUP"seulum; in some cases 



pcnsor, with enibryo. f J, beginning to develop, it remains single, while in 



4, Longitudinal section ol the body or "nu- . t ° 



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



endosperm in enlamed embryo sac ; tf', portion „ .- i -i 



of endosperm broken up; ep. three corpus- lOrm a vertical rOW, and 



cula, from the lower ends of which the suspen- - , i « 



pors, », grow ; p. pollen tube. 1 and 8 X 200 ; m Others a lOUr- Or CVen 



. X 100 ; 4 X 50.-After Hofmeister. ^j^j^^ . ^.^^g^ tranSVCrse 



plane (see Fig. 298, 1) 

 termed a rosette. 



the latter arrangement has been 



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- 



