﻿A TKINSON— COPRINUS 



The second type in the origin of the lamellae has been observed 

 in certain of the Amanitae, in Amanita muscaria by Brefeld (12), 

 mA. rubescens by DeBary (14, 15, 16), and in Amanitopsis vaginata 

 by the writer (Atkinson 10). Here the first evidence thus far 

 observed of the origin of the lamellae is a series of bars or trabeculae, 

 radiating from the stem outward, and attached to both the stem 

 and the under surface of the pileus. These bars appear at first 

 faintly differentiated. The tissue from which they are differentiated 

 is evidently that which is formed by the growth of the primordium 

 of the hymenophore from the under surface of the pileus toward 

 the stem, apparently through the ground tissue of the young 

 basidiocarp. There is no general, annular, prelamellar cavity, 

 not even a weakly developed one. On the lateral surfaces of these 

 radiating bars which are the fundaments of the lamellae, the 

 hymenium is organized, the lamellae begin to separate more and 

 more from each other, and gill cavities or chambers appear between 

 them, while the lamellae are still attached to the stem. 



Just how this growth of the hymenophore primordium advances 

 through the fundamental tissue between the pileus and stem has 

 not been as yet satisfactorily observed, and the same may be said 

 of the organization of the hymenium on the lateral surfaces of the 

 lamellae. It cannot, therefore, be stated at present to how great a 

 degree this "Amanita" type differs from the " Agaricus" type. 



In the forms thus far studied which represent the first type, or 

 Agaricus type, the size of the general annular gill cavity often 

 increases as the plant ages, and the gills are usually quite free from 

 the stem up to maturity. Since in species of Coprinus the gills are 

 attached to the stem at maturity, and separate from it during the 

 later expansion of the plant and the shedding of the spores, the 

 question arose during my study of Amanitopsis, as to whether 

 the origin of the lamellae in such species of Coprinus was like that 

 presented by the Amanita type or not. 



Not only in Coprinus, but in other members of the Agaricaceae 

 the origin of the lamellae presents, at this time, additional interest 

 because in the July number of the American Journal of Botany, on 

 the basis of a peculiar structure observed in Coprinus mkaceus, the 

 statement is made that one of the problems yet to be worked out in 



