REPRODUCTIVE CELLS. 



129 



formation [see Plate iv.]). Endosperm is thus produced 

 after the method known as multicellular formation (see p. 101). 

 In the later endosperm cells of Caltha the intercommuni- 

 cating cytoplasmic fibrils may be readily made out (see 



Fig. 97a). 



Fig. 98 (Diagrammatic). — The Microspore oi" Pinus and the stages 

 TAKING PLACE DURING ITS MATURATION.— a, The young Unmatured 

 microspore. 6, A prothallial cell has been cut o£F. c, The larger cell in 

 h has had another cell cut oflf from it ; this is the antheridial cell ; 

 V, the vegetative cell, d, The antheridial cell has divided into a 

 "stalk" cell, s, and the true generative cell, x,p, is the pollen-tube 

 formed by the elongation of the vegetative cell, e, The nucleus of the 

 generative cell has divided into two, which travel towards the apex of 

 the pollen-tube and lie there in a mass of cytoplasm. (Drawings 

 made from figures at the British Museum of Natural History.) 



