58 THE AGARICACEAE OF MICHIGAN 



the form of a collar which loosens ( secedes i from the stem. Often 

 they are almost free, or, when actuate or adnexed they have a 

 tendency to secede. It is often confusing to find that authors use 

 the term "free" or ''becoming free," when they mean that the gills 

 become loosened from the stem after they have been attached. It 

 is better to use the term "secede" and retain "free" for the usual 

 purpose of indicating that they never were attached to the stem. 

 In the smaller species the gills are often few and therefore 

 very distant. The width is often quite reliable to separate species,, 

 although in some it varies. The STEM is cartilaginous or horny; 

 in a few, e. g., M. oreades it is merely tough-fibrous or with a sub- 

 cartilaginous cuticle. The nature and presence or absence of the 

 villose, tomentose, etc., covering of the stem is used to distinguish 

 some of the sections. The mode of attachment to the substratum, 

 whether rooting or instititious, also helps to separate the subdi- 

 visions. Many of the smaller species have a black stem, and usually 

 the color of the stem in most species is darker below and paler or 

 white at the apex. With the exception of a small number of our 

 species, like G. oreades, G. urens, G. peronatus and G. subnudus, the 

 stem is hollow or slightly stuffed at first. In the small species the 

 stem is almost bristleform and inserted by the attenuated base. The 

 SPORES are white in mass, hyaline under the microscope, varying 

 in shape from subspheriod to lanceolate. The majority have a sim- 

 ilarity in form which is rather striking: round-enlarged at one 

 end and tapering to a pointed apiculus at the attached end. The 

 reviving ability of the gills explains the variability in size which is 

 found at different times in separate plants of the same species. 

 One must be cautious in taking the spore-measurements as in some 

 cases it is clear that the spores continue to grow after the plant is 

 revived by rains. CYSTIDIA are rarely present. In M. colioerens 

 they occur in great abundance in the form of relatively large brown 

 spicules of the same kind as occur on the surface of the pileus and 

 stem. In M. delectmvs they are colorless. The ODOR is strong and 

 often like garlic as in M. scorodonius, M. prasiosmus, M. polijphyUus 

 and M. calopus. In M. foetidus it is very disagreeable, but not of 

 garlic. The TASTE is acrid or bitter in a few species, otherwise not 

 important. 



The arrangement of species is that of Fries. Until the develop- 

 ment is carefully studied for each species, any new arrangement is 

 likely to be unsatisfactory. The genus is divided into two sub- 

 genera: Collybia and Mycena with the following sections: 



