xvi] 



APOGAMY AND APOSPORY 



323 



dial leaf of Ceratopteris thalictroides, in which a stoma is seated only three 

 cells away from an antheridium (Fig. 301). Such developments appear quite 

 inconsequent. It seems impossible to trace any order in them. They appear 

 so varied that it would be possible by using individual cases to deduce 

 almost any morphological conclusion from them. As M. Henri de Cassini 

 has said of the abnormalities of Flowering Plants, " on verrait en elles tout 

 ce qu'on voudrait y voir." 



w^ W- 





,V 



- \ 



>« 



Fig. 299. Nephrodium dilatatiitii, Desv. 

 var. cristatumgracile. Prothalloid cylin- 

 drical process bearing archegonia near 

 its base. It arises by the side of an im- 

 perfect sporangium [sf], and bears a 

 similar sporangium \sp) on the other 

 side, and on the tip are a number of 

 other sporangia associated with ramenta. 

 (X35.) (After Lang.) 



tig ^00 S(olo/Jt.itdritifn7 iils^ait. (jioupofspo- 

 riiigii (>/) on a projection, the structure of 

 which indicates its relation to an archegonium. 

 Occasionally two nuclei are present in a single 

 cell. (x6oo.) (After Lang.) 



In 1894 Strasburger stated generally, for plants showing alternation, 

 that a difference in the number of chromosomes seen on nuclear division 

 showed that the alternating generations differed in nuclear constitution. 

 He recognised the spore-mother-cell in which reduction takes place as the 

 limit between the sporophyte or diploid generation {2n), and the gametophyte 

 or haploid generation {n). He held that the ovum, which on fertilisation 

 has the number doubled, is the limit between the haploid gametophyte and 

 the diploid sporophyte. The general statement of this distinction, which 



