42 THE LARCH CANKER 



scope of the present inquiry. That spermogonia and 

 spermatia can continue to be formed after they have 

 become functionless is shown by the rusts, where first 

 Blackman (1904) and later Christman (1905) and others 

 have shown that fertilization occurs through the fusion of 

 neighbouring hyphae just at the time when the spermatia 

 are shed. The spermatia of Dasyscypha recall those of the 

 rusts in many respects. They are small cells which do not 

 germinate ; they are set free just at the time when the 

 young apothecia are appearing, and they are forced out in 

 a mass of mucilaginous liquid. We are thus justified in 

 calling these organs ' spermogonia ' and ' spermatia ' with 

 de Bary and Willkomm, rather than ' pycnidia ' and 

 ' conidia ' with Brefeld and Massee. In either case they 

 appear to be entirely functionless, and only the vestigial 

 remains of what was once part of the reproductive 

 system. 



Germination of the spores. If ascospores are required for 

 germination, it is essential that they should be ripe and 

 naturally ejected. They may be collected by placing 

 apothecia on damp filter -paper on the bottom of a drop- 

 culture chamber. The spores are ejected in eights, and 

 usually cling to the overlying cover-slip as a cluster ; but 

 not infrequently they are somewhat scattered, five or six 

 appearing in one spot, whilst two or three separate spores 

 hit neighbouring parts of the cover-slip at the same time. 

 Sometimes it is impossible to trace more than six or seven 

 of the eight spores of an ascus, probably because the last 

 one or two spores to leave the ascus are not expelled with 

 sufficient velocity to reach the cover -slip. In support of 

 this view it has been observed that when the cover-slip is 

 raised by another culture-ring placed on the top of the 

 first one, it frequently happens that not more than four of 

 the spores reach the cover-slip. If two rings are placed 

 above the first, making three in all, none of the spores 

 reach the cover-slip, though the apothecia be subsequently 

 proved to be ejecting spores. The height of a culture -ring 

 is 5 mm., so that the maximum distance of ejection of 



