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 
tertilize. 
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 1 (Fig. 271). 
1 In a few species of Equisetum modified underground branches, re- 
sembling a string of tubers are formed, and these give rise to new plants by 
vegetative multiplication. 
