CERTAIN SPECIES OF MucoR 307 
rather a wide range of color in the genus Mucor, varying from 
palest gray (almost white), through yellow and red to dark gray, 
brown, or black. Ridgway (1912) has been used asa color stand- 
ard throughout the work. The nature of the turf is either loose, 
in which case it usually collapses with age, or compact, when it 
remains erect even on the drying out of the culture. 
The relation of the sporangium wall to the columella, as well 
as the shape and size of the latter, is important. The word 
“free’’ has been used to designate the condition in which the 
sporangium wall is separate from the columella and is attached to 
the sporangiophore at the base of the columella; whereas the term 
“‘adnate’’ has been used in cases where the sporangium wall is 
adherent to the columella at its broadened base. (Cf. “nicht 
-aufsitzend”’ or ‘‘libre’’ and ‘‘aufsitzend”’ or ‘‘susjacente.’”’) In 
some species, especially those having globose or oval columellae, 
the shape is constant; in others a wide variation in shape and size 
of columellaeis found. When the latter is true, the small columellae 
are mostly uniformly globose or oval; the large columellae, on the 
contrary, exhibit a strong tendency to a different shape. Thus 
in the descriptions when the shape of the columella is given as 
“oval to pyriform” it is to be understood that the larger colu- 
mellae are mostly pyriform. In a few species, for example Mucor 
varians, the columellae are extremely variable and run the gamut 
of all the shapes. 
In a consideration of the spores the shape and size must be 
noticed, and we find the spores either uniform or variable. If 
uniform, the shape may be globose, oval, elliptical, etc.; if variable, 
some combination of the above-mentioned shapes together with 
irregular spores, subreniform, subfusiform, etc. 
Within certain limits the size of the sporangium is dependable, 
i. e., the sporangia may be large (200-500 u in diameter) or small 
(not exceeding 100 » in diameter and usually 60-80 4). The wall 
of the sporangium is also important, being either deliquescent, 
rupturing, or persistent. 
A certain group of species of Mucor can be separated from the 
rest by the fact that chlamydospores are present in the sporangio- 
phores. Mucor racemosus and M. sphaerosporus would be in- 
cluded in such a separation of species. 
