CLASSIFICATION OF AGARICS 121 



Sulfoformalin. 



Distilled water 25 drops 

 Sulfuric acid, pure o.cc. 

 Formalin {4:% sol.)T5 drops 



The action of guaiac is to turu the flesh blue and should react 

 in one or two minutes. Sometimes only certain parts of the plant 

 react, e. g., in R. subpunctata, the gills are unaffected. The sul- 

 fovanilline turns the parts blue, sometimes at first pink, while the 

 sulfoformalin intensifies the brownish color of the cystidia and the 

 lactiferous hyphae in the gills. We did not test the "cystidia" of 

 the surface of the pileus and stem, where the test was effectively 

 used by Maire. In R. virescens and R. crustosa the last two chem- 

 icals had hardly any effect as compared with the quick reaction in 

 other species. Our work has been merely preliminary and covered 

 only a small number of species. 



The key includes a few species not yet found in the state. Every 

 season seems to differ in the particular species one finds and a num- 

 ber of forms still remain unidentified, but the following list com- 

 prises all the species frequent from year to year, at least in the 

 southern part of the state. 



The genus has been largely gone over and revised since the pub- 

 lication of the Monograph (Mich. Acad. Rep. 11, 1909), and several 

 additional species have been included and others more fully de- 

 scribed and discussed. The recent critical papers by Maire, Eomell, 

 Battaille, Ricken, and others in Europe, have thrown much needed 

 light on a number of species. 



Key to the Species 



(A) Gills unequal, alternately long and short, flesh thick to the margin 

 of the pileus, which is at first incurved and never has striations. 

 (Compactae). 

 (a) Flesh white, unchangeable. 



(b) Gills subdistant; plant entirely whitish; pileus 8-15 cm. 99. R. 



delica Fr. 

 (bb) Gills close. 



(c) P'ileus whitish then sooty-gray, 5-7 cm. broad. 102. R. adusta 



Fr. 

 (cc) Pileus not becoming sooty in age. 



(d) Odor strong, alkaline; pileus large, 10-30 cm. broad, whitish 



then pale rusty-ochraceus. R. magniflca. Pk. 

 (dd,) Odor none; pileus 4-8 cm. broad, whitish. 99. R. decila 

 var. -brevipes Pk. 

 (aa) Flesh changing to reddish or blackish in age or when bruised, 

 (b) Flesh at length incarnate or rusty-reddish; odor disagreeable 



when drying. 104. R. compacta Frost. ' 



(bb) Flesh at length blackish. 



(c) Gills subdistant to distant; flesh at first reddish when bruised, 

 then black. 100. R. nigricans Fr. 



