314 RESEARCHES ON FUNGI 



several hundreds of them together. Many of them germinated, but 

 the compound mycelium resulting did not develop any clamp- 

 connections, from which fact we may conclude that the spores were 

 all of one and .the same sex. Further experiment showed that the 

 sex of these spores was the same as that of the single spore from 

 which had arisen the primary mycelium which had given rise to 

 the fruit-body. This observation confirms a similar one made by 

 Hans Kniep ^ with Schizophyllum comynune. 



As pointed out in Volume II, when a great many spores of 

 Coprinus lagojms are sown on sterilised horse dung in a large 

 crystallising dish, sterile fruit-bodies often come up among the 

 fertile ones. It was surmised that, in all probability, these fruit- 

 bodies arise not on unmated primary mycelia but on secondary 

 mycelia resulting from the union of primary mycelia of opposite 

 sex.2 Mr. Hanna has now proved this by experiment. With 

 sterilised forceps he took a piece of the stipe of a sterile fruit-body 

 which had come up on a culture of polysporous origin and placed 

 it upon nutrient dung-agar, Hyphae at once began to grow from 

 the stipe into the surrounding medium. When examined with the 

 microscope, these hyphae were found to have developed clamp- 

 connections, thus proving that the hyphae of the stipe, and there- 

 fore of the fruit-body as a whole, were of a secondary or diploid 

 nature. Thus we have clear evidence that sterile fruit-bodies of 

 C. lagopus are produced not only by primary mycelia but also by 

 secondary mycelia. 



In general terms, the cause of sterility in fruit-bodies of Coprinus 

 lagopus appears to be lack of vigour in development. This lack of 

 vigour in haploid fruit-bodies arising on haploid mycelia is doubtless 

 due to their abnormal unisexual condition, while in diploid fruit- 

 bodies arising on diploid mycelia in sterilised dung cultures the lack 

 of vigour may be due to partial starvation brought about by the 

 development of more fruit- bodies than the mycelium can properly 

 support with nutriment. 



The fact that monosporous mycelia of Coprinus lagopus give 



1 Hans Kniep, " Uber morphologische und physiologische Geschlechtsdiffer- 

 enzierung," Verhandl. der Physikal.-tned. Gesellschaft zu Wiirzburg, 1919, p. 11. 



2 These Researches, vol. ii, 1922, pp. 73-74. 



