CALAMITES AND LYCOPODS 



375 



or rain. This forms a favorable environment for the 

 multiciliate sperms, which are set free from the antheridia 

 of neighboring male prothallia; and swim to the arche- 

 gonia, and down their neck-canals to the eggs which they 

 fertilize. 



336. The New Sporophyte. — As always, the fertilized 

 egg develops into an embryo, and the embryo, without any 



Fig. 271. — Diagram of life-cycle of Equisetum. 



period of rest, continues to grow until the new sporophyte 

 is formed, with underground rhizome, and finally with 

 the sub-aerial sterile and fertile branches, thus completing 

 the life-cycle^ (Fig. 271). 



1 In a few species of Equiselum modified underground branches, re- 

 sembling a string of tubers are formed, and these give rise to new plants by 

 vegetative multiplication. 



