212 BOTANICAL GAZETTE [September 



development proved to be so similar in all the forms studied that 

 it will be unnecessary to describe it separately for each one. Ac- 

 cordingly, a general account of the method of growth will be 

 given and any minor specific variations noted from time to time, 



Primordium of basidiocarp. — Very young stages in the 

 development of the fruit body were found in only two of the five 

 species, in J. hystrix (fig. 53) and /. geophylla (fig. 70). The 

 button of /". hystrix measures 0.6X0.35 mm., and is composed of 

 loosely interwoven hyphae ranging from 2 to 3 ju in diameter. In 

 the basal end there is a more deeply staining region, conical in 

 shape, where the elements are considerably thicker. This repre- 

 sents the primordium of the stem whose hyphae, multiplying very 

 rapidly, are advancing into the fundamental tissue above. The 

 young button at the right in fig. 70 of /. geophylla is composed of 

 interlaced fibers 1-2 /x thick in the denser stem primordial region 

 inside and 2-4 /x on the outside, where apparently they are dis- 

 integrating and wearing off through the contact with the soil. 



Differentiation of pileus and stem primordia.— The dome- 

 shaped stem primordium at the base of the fruit body continues 

 to advance upward within the fundamental tissue. After a time 

 the hyphae in the apical region, which have been branching pro- 

 fusely and twining in and out through the interstices of the young 

 button, change their general upward direction and radiate outward 

 on all sides (fig. 55). Thus the pileus fundament appears in the 

 form of a more or less globular cap, separated by an annular furrow 

 from the primordium of the stem below (figs. 1, 2, 21, 39, 54, 55, 

 71). This method of progressive differentiation of first the stem 

 and then the pileus from the apex of the former has previously 

 been described by Moller (10) for Rozites gongylo phar a , by 

 Atkinson (8) for Lepiota cristata and L. seminuda, by Douglas 

 (9) and Sawyer (12) for species of Cortinarius, by Sawyer (ii) for 

 Pholiota squarrosa, P. flammans, and P. adiposa, and by Walker 

 (13) for Tubaria furfur acea among the endogenous forms. 



Blematogen. — The remnant of the original fundamental 

 tissue, still enveloping the fundaments of pileus and stem, becomes 

 the true " universal veil," or, as we shall call it, the blematogen. 

 This name was proposed by Atkinson (2, 3) because of the indefi- 



