ALG^E 



127 



little fruit (Fig. 119, B and C, and Fig. 120). The spores 

 it contains produce the alga plants again. 



Such a life-history is more complex than any thus far 

 given. During the growing season the tetraspores multiply 

 the plant; and the life-history may be indicated as follows, 

 P designating the ordinary plant body : 



P tetraspore P tetraspore P tetraspore, etc. 



Such a series, however, does not continue indefinitely; 

 for it is stopped by the coming of an unfavorable period, 

 such a period as winter represents to many plants. In the 

 life-history of our red alga 

 this unfavorable period is 

 bridged by the fruit-like 

 body, just as in the other 

 Algae it is bridged by the 

 heavy- walled oospore. Such 



FIG. 119. One of the red Algae: A, 

 sexual branches, showing antheridia 

 (a), odgonium (o) with its long neck 

 (0 to which are attached two sperms 

 (); B and C, development of the 

 fruit-like body. After KNY. 



Fio. 120. A branch of one of the red 

 Algae showing a mature fruit-ljke 

 body (e), with escaping spores (a). 



