28 



mellae are not common among the 17 or 18 known species. 

 Several species are fairly common but require microscopical 

 study to separate them. B. riihiginosa is abundant and easily 

 recognized. It has obovoid sporangia on stalks about half the 

 total height, and of a uniform reddish-brown or purple-brown 

 color for sporangia and stalks, the latter continuing as colu- 

 mellae. The top of the sporangium breaks away leaving a per- 

 sistent lower part, or there may be a distinct lid, which brings 

 the species close to the genus Craterium from which it is dis- 

 tinguished by the uniformly calcareous capillitium. It is true, 

 however, that short, hyaline threads are sometimes present in 

 this and other species of Badhamia. B. riihiginosa is different 

 in superficial appearance from all species of Craterium. 



Genus 2. PHYSARUM 



This is the largest genus of the Mycetozoa, containing per- 

 haps 70 or more species. The capillitium is the important char- 

 acter and consists of a network of hyaline or pale colored threads 

 with expansions filled with lime granules which are called lime- 

 knots. It differs in that respect from Badhamia where the 

 threads are entirely calcareous, although there are intermediate 

 forms which, sometimes, are difficult to place. The peridium in 

 Physarum has lime granules, and they are frequently present 

 in the stalk and columella. The lime is often colored, and specific 

 distinctions are based on that as well as on sporangial shape, 

 stalk, spores, and other characters, In occasional abnormal in- 

 stances the lime may be scanty or entirely absent. There are 

 many fairly common species among the more abundant of 

 which may be mentioned P. globuliferum which is white through- 

 out in stalk, sporangium and lime-knots. The stalk is calcareous 

 and there is a small, conical columella. The capillitium is per- 

 sistent, which means that when blown free of spores it remains 

 as a globose mass, and it usually has small, rounded lime-knots. 

 P. niicleatum is similar with a persistent capillitium, but with 

 a small, central ball of lime instead of a columella. The stalk is 

 non-calcareous and yellowish in color. P. nutans and P. viride 

 are much alike except in color of the lime in the peridium and 

 lime-knots, which is white in the first and yellow in P. viride. 

 The sporangia in both are somewhat flattened or subglobose, 

 and on stalks that may be partly yellowish and grayish or 



