REPRODUCTION. 



195 



understood a ' ' secondary morphological change ' ' caused by some 

 checking influence on the development of the sporangiophores, 

 which then assume the function of spores. In a book of this kind 

 it is well to adhere to facts obtained from actual observation, and 

 not to enter into too many speculative considerations. 



Among the Oomycetes there occurs reproduction by means of 

 cunidia and swarm-spores, besides the formation of oospores, men- 



FiG. 118. — Achlya lignicola. 

 (After Sachs.) 



Fig. 119.— Formation of 



swarm-spores in AcJdya. 



(After Saclis.) 



tioned above. As an example we may mention AcJdya lignicola 

 as one species of a group of fungi found upon dead flies and other 

 insects, in water, etc. Fig. 118 {^A-E) shows the oospore-forma- 

 tion. Fig. 119 shows the swarm-spore formation. The fungus 

 Phytophthora infci^tans^ which also l)elongs to this group, and 

 which is so destructive to the potato-plant, has no sexual repro 



