SPORES 



33 



and in having a different mode of development, 

 from each other in their mode of development. 



They also differ 



Fia. 50. — Leptothrix och- 

 racea. Showing luode of 

 development of conidia. 



Pia. 51.— Spirophyllum 

 ferrugineum. In state of 

 active conidia-formation. 



Fig. 52. — Leptothrix oeh- 

 racea. Showing conidia ger- 

 minating in situ. 



Conidia (sing, oonidium). These are best seen in some of the iron- 

 bacteria, notably Leptothrix ochracea and Spirophyllum ferrugineum. 

 The mode of their development is 

 shown diagrammatically in Fig. 50. 

 A small wart-like protuberance 

 ©merges from the thread, which, 

 after it has attained a certain size, 

 is cut off by constriction. The 

 small body thus cut off is called 

 a conidium. When one . has been 

 separated off, another is formed in 

 the same place. As under favour- 

 able circumstances conidia are 

 forming all over the organism, 

 and as the conidia after separa- 

 tion do not move away, it often 

 happens that the organism itself 

 is invisible, being buried beneath 

 thousands of conidia (Fig. 51). 

 These bodies are obviously formed 

 for purposes of rapid multiplication. 

 Like the conidia that are produced 



c 



Fig. 53. — Chlamydothrix hyalina. (a) 

 Before gonidia-formation ; (&) during gonidia- 

 formation. (After Migula.) 



