THALLOPHYTES 



69 



out a tube that penetrates between the body segments or through the chitinous 

 skin of the insect. The mycelium finally kills it, filling the body in its vegeta- 

 tive growth. At this stage reproduction begins, the mycelium sending out numer- 

 ous short branches, from which eventually sporophores arise, reaching the surface 

 of the body and 'each abstricting a single conidium, which is squirted off much as 

 is the sporangium in Pilobolus, the dead body of a fly adhering to a window pane 

 often being surrounded by a " halo of spores." 



FIGS. 163-167. Mucor: 163, fertile branches (suspensors) in contact; 164, game- 

 tangia (unequal) cut off; 165, 166, formation of zygospore by two very unequal sus- 

 pensors ; 167, zygospore producing a mycelium, which has already produced a sporangium 

 (after BREFELD). 



Conclusions. The Phycomycetes strongly suggest relationship with 

 the green algae, their coenocytic bodies resembling those of the Si- 

 phonales. They also show a transition from an aquatic (Oomycetes) 

 to an aerial (Zygomycetes) habit, accompanied by a transition from 

 zoospores to aerial spores. There is also an apparent reduction of the 



