DEVELOPMENT 233 



and after a period of rest develops into a hydra. As, how- 

 ever, there are certain abnormal features about the develop- 

 ment of this genus which cannot well be understood by the 

 beginner, it will not be described in detail, but the very 

 important series of changes by which the oosperm of a 

 multicellular animal becomes converted into the adult will 

 be considered in the next lesson. 



