FERTILISATION IN PICEA. 



375 



reproductive cells passes (Fig. 137, B). In specially fortunate 

 sections one may see the smaller spermo-nucleus pressed against 

 the larger oonucleus (Fig. 137, C), and then the two unite into the 

 embryo-nucleus. The apex of the pollen-tube in Picea is finely 



m 



FIG. 137. Picea rulgaris, Lk. .1, a ripe oosph ere with nucleus, on, and ventral 

 canal-cell, d. B, an oosphere during fertilisation ; sti, the intruded spermo-nucleus ; 

 <;, the oonucleus ; p, the tip of the pollen -tu lie. C, an oosphere during fertilisation, 

 showing the conjugation of spermo- and oo-nucleus. D, the four nuclei in the end 

 of the oospore remote from the neck, only two of which can be seen, since they all 

 lie in the same plane. K, the nuclei have divided ; four nuclei lie now at the end, 

 and tour others more in the body of the oospore. F, three stages of cells are formed 

 in the end of the oospore. '?, the middle stage has elongated, and carried the lowest 

 stage into the endosperm. The cells of the lowest stage are specially rich in contents 

 (x90). 



porous, and in species of Piniis shows a clear pit, which, however, 

 does not suffice for the passage of the nucleus ; but still the mem- 

 brane at the tip of the pollen -tube is soft and swollen, so that it 

 would offer no great resistance to the passage of the nucleus. 



