Spermogonia and S-permatia. 15 



Massee also considers the aecidium to be a sexual product, and both 

 authors ag,ree that the spermatia are not concerned in it. If the spermogonia 

 and aecidia represented male and female reproductive organs, a distinct 

 alternation of generations would be present, the spore-bearing stage or 

 sporophyte commencing with the fertilized cell in the aecidium, and the egg- 

 bearing stage or gametophyte starting with the uni-nucleate teleutospore. 

 But the most probable view is that the spermatium is a functionless organ, 

 and its presence is an indication that the ancestors of the rusts may have 

 possessed an alternation of generations similar to that referred to above. 



