THE LARCH CANKER 



45 



to each other. Further evidence, however, would be neces- 

 sary to substantiate this view. 



For a fusion to take place it is of no consequence whether 

 the two hyphae are branches of the same mycelium or not, 

 and a number of spores germinating together form a close 

 network in which it is impossible to determine from which 



FIG. 21. The growth of mycelium in drop cultures : sp., spore. 



spore many parts of the mycelium have arisen. Such a net- 

 work is best seen in cultures in distilled water, as until the 

 hyphae become starved the fusions are not so frequently 

 formed. 



In such cultures the primary germ tubes become markedly 

 septate (fig. 21, B), the septa being usually 12-20 p. apart. 

 But the branch hyphae which arise from these are often quite 

 unseptate, and septa, when present, are far apart. As the 

 available food supply is used up, drops of some liquid 

 (probably an oily substance) appear, which become more 

 numerous as the segments die. I have often noticed that 

 some segments die before others and lose their turgidity, 

 and then the more turgid ones are markedly refringent and 



