14 Mycetozoa of North America 



Sporophores densely compacted to form a honeycomb-like 

 structure. 



Type locality: Europe. 



Habitat: On rotten wood; common and abundant. 



Distribution: Throughout North America. 



Illustration: Lister, Mycetozoa ed. 3. pi. 1. 



The two varieties are useful for purposes of classification, but 

 depend entirely upon meteorological conditions prevailing during 

 the period of fructification. C. arbuscula and C. filiforme cited 

 as synonymous with var.flexuosa are not separable, as they occur 

 together in the same developments. Var. flexuosa forms under 

 perfect drying conditions, usually on a higher or drier habitat. 

 It is the most perfect development of the species. Var. porioides, 

 on the contrary, develops closer to the ground and under wet 

 conditions. If, at the proper time of development of var. porioides, 

 the conditions of moisture change slightly to drier, the resultant 

 fruit may show the variety and the typical form from the same 

 Plasmodium; specimens exhibiting the transition are found oc- 

 casionally. The Plasmodium of C. fruticulosa is sensitive to cer- 

 tain stimulants, perhaps food, and may be faintly colored, indicat- 

 ing the various tints observed sometimes later in the fruiting 

 bodies. Var, caesia, found so far only in Germany, is bluish or 

 bluish green, developing from a similarly colored plasmodium. 



Dr. G. W. Martin reported the collection of specimens in the 

 Panama Canal Zone and in Costa Rica (Mycologia 34: 698. 

 1942), which he believes agree with the description and figures of 

 Ceratiomyxa sphaerosperma Boedijn (Misc. Zool. Sumatrana 24: 1. 

 1927). Authentic material from Sumatra is unavailable now 

 because of world-wide conditions. This may be another species 

 of Ceratiomyxa, and if so, it should occur in the tropics generally, 

 as Ceratiomyxa is abundant there, particularly C. fruticulosa var. 

 flexuosa. It may, however, be only a phase of C. fruticulosa, 

 which in a number of specimens here from the American tropics 

 discloses variation not seen in specimens from the temperate 

 zones. Similar conditions of variation between tropical and 

 temperate forms are found in other species, notably in Diachea 

 bulbillosa. I believe with other students that there is but a single 

 species of Ceratiomyxa, the fruiting bodies of which may be modi- 

 fied by external conditions at the time of development. These 

 modifications extend to such extremes as vars. flexuosa and 

 porioides, but are not confined to them solely. The description 



