404 



STRUCTURE AND LIFE HISTORIES 



through the neck-canal of the archegonium, into the 

 archegonial chamber. Fertilization, here as always, is 

 completed by the fusion of the sperm and the egg-nuclei 

 (Fig. 301). The behavior of these little sperms in an allied 

 genus, Zamia, is thus described by their discoverer, 1 

 Webber: 



FIG. 301. Fertilization in Zamia floridana. The male and female nuclei 

 are fusing; b, remains of the cilia of the sperm. (After Webber.) 



"In removing the nearly mature pollen- tubes the sperm- 

 atozoids are found to be in various stages of development, 

 as would be expected. In many cases tubes have been 

 observed, before cutting them off, in which the two sper- 

 matozoids had pulled apart and were swimming free in the 

 protoplasm. In some instances their movement in the 

 pollen- tube, before it is injured, can be observed with the 

 aid of a hand lens. 



"It is an interesting sight to see the two giant sper- 

 matozoids moving around vigorously in the pollen-tube, 



1 Motile sperms were discovered in Cycas in 1897, by a Japanese botanist, 

 Hirase, following their discovery in Ginkgo in 1896 by another Japanese 

 student, Ikeno. The latter was the first discovery of motile sperms in a 

 spermatophyte. 



