PSALLIOTA CAMPESTRIS 435 



protoplasm, and a less amount is present in the cells of the trama. 

 Part of this protoplasm and its inclusions, such as glycogen, etc., 

 is doubtless used up in the growth of the basidia in length and of 

 the paraphyses in breadth, and part of it is necessary for the 

 formation of the sterigmata and the spore-walls. Part of it must 

 also be used up in processes of destructive metabolism, including 

 respiration. But there can be little doubt that most of it is 

 destined to pass through the narrow sterigmatic necks and to be 

 crowded into the spores, there to await the important process of 

 germination and the construction of germ-tubes. As more and 

 more generations of basidia shed their spores, the hymenium, sub- 

 hymenium, and trama become more and more emptied of proto- 

 plasm, until, when the process of spore-discharge ceases, the cells 

 are all occupied by large vacuoles. The contrast in density between 

 a section of a gill which has just begun to shed spores, and of a 

 gill which has just ceased to shed spores, is very striking. No 

 doubt, chemical analysis of two such sections would show a very 

 marked difference in proteins and other cell-contents. There is 

 every reason to suppose that a mushroom must be much more 

 nutritious when it is young than when it is aged, for the most 

 desirable food substances which it contains are gradually carried away 

 from the pileus by the spores during the spore-discharge period. 



The Hymenium of the Wild Mushroom. Up to the present 

 we have confined our analysis of the hymenium to the cultivated 

 form of Psalliota campestris. We shall now turn to the wild form, 

 the hymenium of which is similar in all essentials of its organisa- 

 tion to that of the cultivated form, although it exhibits some 

 interesting differences in detail. The main points of difference 

 are : (1) the Wild Mushroom, typically, has quadrisporous basidia 

 and the Cultivated Mushroom bisporous ones, (2) the basidia of 

 the Wild Mushroom are distinctly larger than those of the 

 Cultivated, and they produce longer spores (cf. Figs. 148 and 149 

 with Fig. 147, p. 429). 



The cross-section of the Cultivated Mushroom represented in 

 Fig. 147 (p. 429), which has just been described, is a synthetic one, 

 embodying as many morphological details as possible ; but it 

 is unaccompanied with drawings of any of the special sections 



