COPRINUS COMATUS 157 



the hymenium must all bear full-sized spores at one and the same 

 time makes the presence of sterile elements, such as the paraphyses, 

 imperative. If- one were to take away the paraphyses and crowd 

 the basidia together so that their bodies were touching, since the 

 four spores on each single basidium require more lateral space in 

 which to spread themselves than the basidium-body, the spores on 

 adjacent basidia would jostle one another and mutually hinder 

 both development and discharge. Nothing but confusion would 

 result, and the beautiful organisation of the hymenium would be 

 destroyed. If one were to remove the paraphyses and leave the 

 basidia in their original positions, the basidial bodies would be 

 naked and unsupported throughout their whole length, in conse- 

 quence of which they would doubtless have much greater difficulty 

 in keeping their axes perpendicular to the general surface of the 

 hymenium and would be much more likely to suffer, should transpira- 

 tion of water from their surfaces exceed a certain minimum. I think 

 it probable that the paraphyses are important in helping to secure 

 the proper spatial arrangement of the basidia in the first instance, 

 when the elements of the hymenium are undergoing their initial 

 organisation. The first elements in the hymenium to attain their 

 full lateral extension are the basidia ; and, at the moment when this 

 extension has just been completed, the paraphyses are relatively 

 small and still capable of considerable growth in a plane parallel 

 to the surface of the gill. As the gill gets older, the paraphyses at 

 least double their superficial area. The paraphyses are therefore 

 the elastic elements of the hymenium, and all the later stretching 

 of this structure, which is important in the turning outwards of the 

 gills at the base of the pileus, is accomplished by them. That the 

 paraphyses give mechanical support to the basidia is sufficiently 

 obvious ; and that they pass food materials to them when they 

 are becoming filled with the substances which are destined to be 

 crammed into the spores, and that they supply them with water 

 according to their needs, seems sufficiently probable. The extension 

 of the paraphyses during the development of the hymenium in 

 Coprinus sterquilinus will be discussed with the help of illustrations 

 in the next Chapter. 



It has been shown that the long and short basidia and the para- 



