302 DIVISION II. COURSE OF DEVELOPMENT OF FUNGI. 



smaller towards the under surface of the pileus or hymenophorum ; this consists itself 

 of numerous layers of hyphae which run in an undulating course from the middle of 

 the pileus to its margin and give off the hyphae of the trama as branches. The 

 subhymenial tissue is composed of small isodiametric cells, which show plainly by their 

 arrangement that they are members of the delicate short-celled interwoven hyphae. 

 The laticiferous tubes appear both in the hymenophorum and in the trama ; in the 

 former they usually run parallel to the principal hyphae, while in the trama they spread 

 in abundance in every direction and are much branched. The structure of the trama 

 in Russula, and according to Hoffmann in Lactarius mitissimus also, is for the most part 

 pseudo-parenchymatous. 



Schizophyllum, a genus of the Agaricineae, differs from the rest in the structure of 

 the lamellae. The lamellae are formed in this case, as in other genera, as projections 

 from the hymenial surface, but they split from the edge to the middle parallel to 

 the surfaces into two plates which curve away from one another as they continue to 

 grow. The dorsal surfaces which are convex to one another are sterile and hairy with 

 spreading hyphal branches ; the concave surfaces answering to the surfaces which bear 

 the basidia in undivided lamellae with the interstices between them bear the hymenium. 

 JFistulina so far agrees with Schizophyllum that its hymenium is beset with small 

 tubes, which bear the hymenium on their inner face and are barren without ; only the 

 tubes are formed separate from the first, according to the accounts which we possess, 

 and not by the splitting of the trama of reticulately connected projections. 



The hymenial layer itself consists of the terminal members of the subhymenial 

 hyphae closely packed together and placed vertically to the surface. The larger 

 number of these cells develope into basidia. Others may remain sterile and then 

 they surround the basidia as the paraphyses surround the asci and may there- 

 fore be called by that name. They appear to be the hymenial tissue of LeVeille* 

 which he distinguishes from the basidia in his fundamental researches into the 

 hymenium of the Mushrooms. It is uncertain whether they can be entirely 

 wanting; yet it has been expressly stated by more recent observers that in some 

 cases the hymenium contains only basidia, for example by De Seynes in the 

 case of Fistulina hepalica, and many other descriptions say the same thing by 

 implication inasmuch as they speak only of basidia. The fact is that in many cases 

 amongst undoubted spore-abscising basidia there are present only structures that 

 may possibly prove to be paraphyses, but which are so very like the basidia, differing 

 from them at most in their somewhat smaller size, smaller amount of protoplasm and 

 present sterility, that it is not possible to say when they are examined in prepared 

 specimens whether they might subsequently have assumed the function of basidia or 

 not. This is the case with Agaricus melleus 1 . From these circumstances the organs 

 in question have often been termed sterile basidia, a name descriptive of the 

 appearance in all cases, but requiring critical examination. 



On the other hand, cases are known in which the elements between the basidia 

 differ from them entirely in their character. The bowl-shaped compound sporophore 

 of Corticium amorphum, Fr. may be mentioned especially in support of the expression 

 paraphysis, in which a few long club-shaped basidia are found between a large number 

 of narrowly filiform branched hairs often constricted into the form of a rosary, so that 

 the sporophore would be thought at first sight to belong to a Peziza rather than to a 

 Hymenomycete 2 . It has long been known that the larger portion of the surface of 



1 Hartig, Krankhcitcn (1. Waldbaume, t. II. - Ilartij,', 1. c. t. V. 



