PHYSARACE& 21 



This sequence is meant to convey the idea that the presence 

 of lime is indicative of differentiation less complete. That the 

 plasmodium should at the outset eliminate, by refusing the 

 unnecessary lime, is indicative of higher rank than that the lime 

 should be carried until the last and then be crystallized out, 

 or excreted by simple desiccation. The circumstance that the 

 excreted lime may sometimes serve a protective purpose in 

 the fruit, does not vitiate the general principle. In Series B 

 the differentiation reaches a climax in the perfected capillitium 

 of the Trichias. 



ORDER I. 

 PHYSARACE^E. 



Spores violaceous black. The capillitium usually delicate and 

 thread-like ; peridium and capillitium, one or other or both, 

 more or less extensively surcharged with lime. Peridium simple 

 or double. Fructification various. 



This order is recognizable by several characteristics, but is 

 especially marked by the peculiar lime deposits which affect 

 the capillitium or peridium, now one, now the other, more often 

 both. 



As here defined, the order Physaracece includes two distinct 

 families ; of the one Physarum, of the other Didymium, is type. 



Key to the Families of the Order Physaracese. 



A. Fructification calcareous throughout ; capillitium intricate, PHYSARE^E 



B. Calcareous deposits confined to the peridium ; capillitium simple, 



DlDYMIEjE 



A. PHYSAREyE. 

 Key to the Genera of the Physarese. 



A. Fructification asthalioid . . . . . . . I. FULIGO 



B. Fructification plasmodiocarpous or of distinct sporangia. 



a. Peridium without lime. 



i. Plasmodiocarpous 7. CIENKOWSKIA 



ii. Sporangia distinct . . . . .8. LEOCARPUS 



