PANAEOLUS CAMPANULATUS 303 



Here, in the tubule, all the spermatozoa appear to be quite 

 ripe but are still held in place by the nurse cells (cells of 

 Sertoli) in which they were nourished. A little farther along the 

 tubule, the spermatozoa are being set free. Still farther along, 

 it is evident that the spermatozoa have been recently liberated 

 and that preparations are under way for the formation of their 

 successors. Still farther along, a new crop of spermatozoa is partly 

 developed. Still farther along, the spermatozoa are all ripe and 

 thus resemble those which were first observed. Wave after wave 

 may thus be traced in one and the same tubule ; and, doubtless, 

 each part of every tubule produces a series of successive generations 

 of spermatozoa. Thus the development of spermatozoa by the 

 epithelium lining the tubules of the testis of a Mammal very 

 much resembles in its time and space relations the development 

 of basidiospores by the hymenium covering the flat and exposed 

 giUs of Panaeolus campanulatus . It seems, therefore, that the 

 problem of efficiency in the production and liberation of vast 

 numbers of minute organic particles has been solved in the 

 same way by the higher animals and by a lowly toadstool. 

 Just as a fruit-body of Panaeolus is organised so that, through- 

 out its period of functional activity, it liberates a constant stream 

 of milhons of spores into the air, so the testis of a Mammal is 

 organised so that, throughout its functional activity, it liberates 

 a constant stream of millions of spermatozoa into its tubules. 

 The spores are set free as soon as they are ripe, so that they may 

 be scattered by the winds and thus find new substrata for the 

 development of new individuals of the species. The spermatozoa, 

 which are simply male gametes, are confined in a storage chamber 

 and ever renewed, so that they may be always ready for employment 

 in a sexual act. 



The Spores which are Wasted. Whenever one examines a 

 fruit-body of one of the Hymenomycetes at the end of the spore- 

 discharge period, one finds that it has adherent to its gills a 

 considerable number of spores which for some reason or other 

 have failed to be properly liberated. These spores, since they 

 contribute nothing to the dispersal of the species in nature, may 

 be called wasted spores. 



