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1920J DOUGLAS— I XOCY BE 213 



niteness in the application of the former term by the earlier writers. 

 Although there are minor differences in its character and con- 

 siderable variation in its final disposition, it has been found to be 

 a homologous structure in all endogenous forms. In the Amanita 

 type, as illustrated by Amanitopsis vaginata (4), the blematogen is 

 separated from the pileus by a clean-cut cleavage layer and forms 

 the volva. In all the other forms it becomes more or less " con- 

 crete" with the pileus, so that in the majority of cases it is impos- 

 sible to distinguish where the pileus leaves off and the blematogen 

 begins. In Agaricus forms (1, 2, 6) considerable blematogen enters 

 into the formation of the cortex of the pileus. In others it be- 

 comes the cuticle (Cortinarius anfr actus and C armillatus, 9). Often 

 it is shed in the form of scales (Cortinarius distans, 9) which may 

 be mealy or powdery (Lepiota cristata, 8, Coprinus micaceus, 7). 

 In Pholiota (11) scales are formed from the blematogen which 

 partly gelatinize. Frequently fibrillose scales of blematogen per- 

 sist in the mature plants, as in Lepiota clepeolaria (5) and Coprinus 



comatus (7). 



In four of these species of Inocybe the blematogen is a very 

 delicate structure, which very soon disappears from the surface of 

 the pileus. In /. obscura (pi. XVIII), /. infelix (pi. XIX), /. enthe- 

 loides (pi. XX), and /. hystrix (pi. XXI)' the pileus seems to expand 

 through the blematogen to the surface, where it gives off the char- 

 acteristic silky Inocybe fibrils. There is a gradual transition in 

 the size of the hyphae from the inner ones, about 2 /i in diameter 

 in the denser region, to the loose radiating ones on the outside 

 which measure 4-6 n in thickness. These on the outside take the 

 stain more deeply than those within, and behave generally as 

 disintegrating hyphae. 



The condition is slightly different in /. geophylla, which belongs 

 to a section of the genus characterized by a pileus which does not 

 crack and which is covered with interwoven fibrils. That these 

 interwoven fibrils are of blematogenous origin seems clear from 

 the fact that they appear in the early stages before the pileus 

 primordium has advanced to the surface of the fruit body (fig. 71). 

 They form a deeply staining thin envelope over the whole of 

 the developing basidiocarp. This envelope might possibly be 



