THE LARCH CANKER 



41 



able period in the cavities. The cavities usually, though 

 so far as .1 can determine not invariably, connect with the 

 outside air by irregular mouths, which are mere gaps in the 

 mycelial cortex, and are not lined by specialized hyphae. 

 Through these mouths the spermatia are forced out by the 

 formation of numerous younger ones behind, and often 

 remain in masses stuck together by a mucilaginous liquid 

 which is exuded with them. 



These spermatia are quite functionless, and, as the name 

 implies, are regarded as vestigial male cells. Many botanists 

 now consider them to be functionless 

 conidia. The reasons against this view are 

 shortly as follows. 



Firstly, they will not germinate. Massee 

 (1902) describes and figures cells, which he 

 considers to be conidia, germinating by 

 normal germ tubes in the presence of 

 sections of larch bark. But the cells 

 which he describes are round and larger 

 than spermatia, and bear an intimate 

 resemblance to conidia of Penicillium sp., 

 which grows commonly on the apothecia 

 of DasyscypJia. Brefeld (1891), who also 

 regarded these cells as conidia, states that Dr. Moller, working 

 in his laboratory, found, that they became slightly swollen 

 when placed in a nutrient solution, but did not germinate. 

 This incapacity for germination is normal in spermatia, 

 whose only function is fertilization ; but it is not easy to 

 understand why conidia should ever become functionless in 

 this way. 



Secondly, we know from the researches of Baur (1898), 

 Darbishire (1900), Thaxter, &c., that in some Ascomycetes 

 fertilization is still effected by means of spermatia. In 

 other Ascomycetes fertilization by spermatia has been 

 replaced by fecundation by a hypha in proximity with the 

 female organ, or by the fusion in pairs of the nuclei in this 

 organ. Probably one of these methods obtains in Dasy- 

 scypha, but the investigation of this point is outside the 



FIG. 19. Ascus 

 which has dis- 

 charged its spores. 



