4G6 COMPARATIVE MORPHOLOGY OF FUNGI 



single collection by Duss from Guadaloupe contained a specimen of 

 Psathyra near P. gyroflexa, but with no indication that it came from the 

 same mycelium. Subsequent field studies over a long period by Petch 

 have failed to find a normal agaric growing with this genus. While 

 superficially Rhacophyllus resembles the agarics, its ontogeny suggests 

 rather Gasteromycetous affinities, such as Podaxon, Gyrophragmium, 

 etc., but none of these genera have been sufficiently studied to determine 

 relationships. 



Hemigasteraceae. — As an appendix, we have retained this interesting 

 form in the position suggested by Juel (1895) although it might be 

 interpolated in the developmental series leading to Secotium in the 

 Hysterangiaceae as suggested by Gaumann (1926). Its development 

 suggests that of Boletus flavus on a smaller scale. In Hemigaster candidus 



.»■**<■;.' ■::•• .vv.. ■ ■* •• 



;i .^:V 



■j'-i-.v-V ■"•l*v>. 





1 m 



f*Mm 



Fig. 296. — Hemigaster candidus. 1. Coremium of diverging hyphae which form the 

 fundament of the pileus. 2. Older stage. Pileus more distinct, with the young hymenium 

 below. 3. Immature fructification. On the sides of the middle column grow the gemmae- 

 forming hyphae. (1, 2 X 50; 3 X 27; after Juel, 1895.) 



on rabbit dung in Sweden, the fundament of the fructification consists 

 of a spherical knob of closely intertwined hyphae (Fig. 296, 1) which 

 extend to the top of the head, almost parallel, then outward and down- 

 ward. The tips bend downward at a right angle on the lower side, 

 forming the fundament of the hymenium (Fig. 296, 2). Eventually the 

 hyphae on the margin of the pileus grow to and fuse with those of the 

 stipe, forming a closed annular chamber (Fig. 296, 3). The outer layer 

 of the pileus differentiates into a loose outer and a firm inner layer sur- 

 rounding the pileus. The outer two thirds is occupied by hymenium con- 

 sisting exclusively of four-spored basidia with small, smooth, ellipsoidal 

 spores. The inner third is filled by a hyphal tissue which grows from 

 the stipe within the annular furrow and develops on lateral branches, 

 numerous, sub-sessile, occasionally catenulate gemmae. In the following 

 period, the head containing the chamber expands horizontally and is 

 almost filled by increasing masses of gemmae. At maturity, the gemmo- 

 phores disintegrate and the chamber contains a powder of free basidio- 

 spores and gemmae. 



