28 RESEARCHES ON FUNGI 



the number of nuclei in the basidia and spores. Never once did 

 he actually observe one and the same basidium in the living state 

 produce more than one generation of spores. He deduced his 

 conclusions from his nuclear studies. Now my experience, based 

 upon extensive observations on the living hymenium, is that a 

 basidium never produces more than one generation of spores and 

 that, after producing a single crop of spores, its sterigmata and 

 body quickly collapse. In writing of Calocera cornea, Maire states 

 that the secondary (fusion) nucleus of the basidium divides to form 

 either two or four daughter nuclei, and that in the latter alternative 

 there are two generations of spores : each spore receives only one 

 nucleus. 1 Now my observations on the fruit-bodies of Calocera 

 cornea, which are epitomised in Fig. 2 (p. 7), go to prove that a 

 sterigma, soon after shooting away its spore, collapses. This was 

 observed for living basidia not once but several times. In 110 case 

 did I see a sterigma produce two spores in succession. Direct 

 observations, therefore, do not support Maire's assumption. 



In the cultivated Mushroom (Psalliota campestris) and in 

 Coprinus bisporus Lange, the basidia are disterigmatic and there- 

 fore produce only two spores at one time (Fig. 8, p. 18). In both 

 these fungi, as I have observed by examining the living hymenium, 

 there is only one generation of spores. In the Coprinus, each 

 basidium, soon after shedding its spores, becomes involved in the 

 upward moving zone of autodigestion and is therefore destroyed 

 before there is any possibility of its producing a second generation 

 of spores. In the Mushroom, shortly after a basidium has dis- 

 charged the second of its two spores, its sterigmata collapse and its 

 body shortens and sinks down into the hymenium. It can then 

 be seen with two sterigmatic stumps at its outer end. In this 

 condition it is no longer living. There is therefore not the slightest 

 direct evidence to support the supposition that a basidium of 

 Psalliota campestris ever produces two generations of spores. 2 



There is a relation between the volume of a basidium and the 



1 Rene Maire, loc. cit., p. 78. 



2 The collapse of the bisporous basidia of the cultivated Mushroom takes place 

 in exactly the same manner as that of the quadrisporous basidia of the wild 

 Mushroom. The phenomenon of basidial collapse will be dealt with in more 

 detail hi later chapters, e.g. Chapter X. 



