136 



THE BIO LOOT OF A PLANT. 



nences occurring upon the posterior part and the under side of 

 the prothallium, often among the rhizoids. When fully formed 

 (Fio-s. 70, 71) an antheridium consists of a mass of rounded cells 

 {sperinatozoid mother-cells) enveloped by a membrane one cell 

 In tliickness. 





i.h-. 









m 



Fig. 70. (After Suminski, slightly modified.)— Adult prothallium of Fter\B serrulata 

 seen from below, showing the rhizoids (r) at the posterior end, the depression at 

 the anterior end ; the cushion near the latter bearing (in this case) four arche- 

 gonia. Among the rhizoids are the (spherical) antheridia. The chlorophyll- 

 bodies only are shown in the cells of the broad plate of tissue constituting the 

 prothallium. Just above the anterior depression is seen a rrothallium of the 

 natural size. 



Fig. 71. (After Strasburger.)— Mature an- 

 theridium of Pterin- sej7tt?<xf ft. p, periphe- 

 ral cells; m, mother-cells of the sper- 

 matozoids. 



Fig. 72.— Diagram to illustrate the ori- 

 gin of an antheridium. A, very 

 young stage; B, older; a, original 

 epidermal cell enlarged ; b, mother- 

 cell of the entire antheridium. 



