PANAEOLUS CAMPANULATUS 311 



in Volume III, is most marked in the various species of Coprinus, 

 but it is also very strikingly displayed in Lepiota cepaestipes and 

 Psathyrella disseminata. In the fruit-bodies of all these species, 

 the basidia can be separated into different classes according to their 

 length ; and, in a single species, they are dimorphic, trimorphic, 

 or quadrimorphic. Subsequently it will be shown that the differ- 

 ential protuberancy, where polymorphism of the basidia occurs, 

 is correlated with the crowding of the basidia and is necessary to 

 prevent the spores of adjacent basidia from touching one another 

 and sticking together. For the present, therefore, let us take it 

 for granted that basidial protuberancy, where most strongly 

 developed, is evidently related to the mechanical requirements 

 of the spores, i.e. to the provision of a free space for spore- 

 development and spore-discharge. 



In the fruit-bodies of the Panaeolus Sub-type the basidia are 

 monomorphic, i.e. when mature they are all about equally pro- 

 tuberant beyond the general level of the hymenium. The question 

 arises : why should these basidia be protuberant at all ? I shall 

 attempt to answer this question in connection with Panaeolus 

 campanulatus. First, it is to be remarked that the protuberancy 

 of any basidium in the hymenium is strictly temporary : it is 

 acquired shortly before the development of the spores, and lost 

 almost immediately after the spores have been discharged. 

 Evidently, basidial protuberancy is connected with the develop- 

 ment and discharge of the spores. It seems to me that the 

 lengthening of the maturing basidia, which results in their becoming 

 protuberant, is of considerable advantage to the functional activity 

 of the fruit-body in the following respect : it causes the spores, 

 which develop on the basidia only after these have become pro- 

 tuberant, to take their origin, grow to maturity, and be discharged 

 above the general level of the hymenium in spaces which are 

 mechanically free from neighbouring hy menial elements. 



We have seen that, owing to various imperfections, a certain 

 number of spores, instead of escaping freely from a fruit-body, 

 become wasted in that they stick tenaciously to the hymenium. 

 Now there is always some danger that the waste spores of one genera- 

 tion may become obstacles to the development, and particularly 



