PSALLIOTA CAMPESTRIS 441 



but more usually either basidia or cells supporting paraphyses ; 

 from the lowest layer, cells nos. XIV, XV, XVI, XVII, XVIII, 

 and XIX, arise sometimes a basidium as at XVIII, but more 

 frequently cells of the second layer of the subhymenium. Here 

 again, it is clear that there is no level plane separating the 

 hymenium from the subhymenium. The basidium no. 3 arises 

 from one of the lowest cells of the subhymenium, whereas the 

 basidia nos. 11 and 5, etc., arise at a higher level, and the para- 

 physes nos. 14 and 16, etc., at a still higher level. The oldest 

 basidia, i.e. those which produce spores first, are as a rule the 

 longest, owing to their depth of origin in the subhymenium. 

 Basidia of later generations tend to arise more and more super- 

 ficially, so that their shafts become shorter and shorter. In this 

 particular section, the basidia nos. 1, 2, and 3, which alone are 

 producing spores, are the most deep-seated so far as their origin is 

 concerned. 



Between the subhymenium and the swollen cylindrical cells 

 of the trama, there are often placed a certain number of thin 

 elongated hyphae. One of these happens to be present in Fig. 149. 



The last of the sections of the very young hymenium, cut at the 

 same time as the two just described, is represented in Fig. 150. 

 In cutting and mounting the section, all the spores on basidia 

 nos. 1, 2, 3, 4, and 5 were knocked off their sterigmata except the 

 one shown on no. 1. Probably the spores on all these basidia were 

 nearly ripe and, on this account, easily detachable. None of the 

 spores accidentally removed are restored in this Figure, so that 

 the present-generation basidia are all represented in their mutilated 

 condition. It may be asked : is it not possible that the basidia 

 nos. 2, 3, 4, and 5 are really basidia which have just shot away 

 their spores ? The answer is no. These basidia all contained a 

 certain amount of massive protoplasm in their upper ends (not 

 shown in the illustration) which was doubtless still being passed 

 into the spores ; but such protoplasm is not contained in basidia 

 which have just shot away their spores. Moreover, basidia which 

 have shot away their spores usually collapse about twenty minutes 

 after the discharge of the last spore. It is most unlikely that four 

 basidia, which have discharged all their spores and are all about 



