112 RESEARCHES ON FUNGI 



A tiny drop of water is excreted at the hilum of each spore just 

 before discharge, and the drop is carried with the spore. The means 

 employed for proving that the drop is carried with the spore was 

 fully described in Volume 11.^ 



The spore-bearing basidia are scattered over the hymenium in 

 the manner characteristic for the Armillaria Sub-type (Fig. 52). 

 The older basidia with nearly ripe spores are well separated from 

 one another and younger spore-bearing basidia come up between 

 them in a scattered manner. There is no compact grouping of 

 spore-bearing basidia of like age such as we find in Panaeolus 

 campanulahis . 



Concluding Remarks. — The Armillaria Sub-type, in which spore- 

 bearing basidia of about the same degree of maturity are set distantly 

 apart with younger spore-bearing basidia coming up between them, 

 includes a considerable number of species belonging to the Leuco- 

 sporae and the Rhodosporae. 



Associated with the loose arrangement of the hymenium in the 

 Armillaria Sub-type there is, on the whole, a relatively rapid develop- 

 ment of the individual spores as compared with the Panaeolus 

 Sub-type. This is shown in the table on p. 113.2 



Finally, one may ask : which is the more primitive arrangement 

 of the hymenium, the loose one of the Armillaria Sub-type or the 

 compact one of the Panaeolus Sub-type ? The former seems to me 

 to be the more primitive. One may suppose that there is more 

 detailed co-ordination between the elements of the hymenium in 

 securing the compact arrangement and the successive development 

 of a series of generations of basidia in a Panaeolus, than is displayed 

 in the loose arrangement of the hymenium exhibited, say, in 

 Collyhia velutipes. It seems probable that the Porphyrosporae and 

 the Melanosporae, with their highly pigmented spores, haVe been 

 evolved from the Leucosporae, with their colourless spores, and that, 

 during the transition, the compact type of hymenium was developed 

 from the loose type. Also the hymenium of the Armillaria Sub- 

 type may be regarded as more primitive than that of the Psathyrella 

 Sub-t3'pe, in which the basidia are specialised to the extent of being 



^ Researches on Fungi, vol. ii, 1922, pp. 15-17, also Pig. 7. 

 2 The data are taken from vol. ii, 1922, p. 44. 



