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A TEXTBOOK OF THEORETICAL BOTANY 



cells now undergo a number of divisions, forming a mass of 128 tiny cells 

 lying freely in a space formed by the breakdown of the outer cells. This 



Prothallus tissue 

 Megaspore wall' 



Fig. 595. — Selaginella kraussiana. Development of the female 

 gametophyte. A and B, Early stages showing contracted proto- 

 plast and exospore and mesospore separated by a space con- 

 taining a gelatinous membrane. C, Protoplast expanded forming 

 a hollow sphere in the megaspore. Nuclei arranged apically and 

 increasing in number. D, Protoplast beginning to thicken to 

 fill the central space and dividing apically into female gametophyte 

 cells. E, Mature gametophyte iDounded below by the diaphragm, 

 the remainder of protoplast dividing into cells. F, Embryo with 

 suspensor, developing in nutritive tissue below the diaphragm. 



Structure we regard as an antheridium, the eight outer cells forming its wall, 

 and the central cells representing the antherozoid mother cells, from 

 each of which at maturity an antherozoid develops. The antherozoid is an 



