140 A. E. HILTON ON SPORANGIAL CHARACTERS OF MYCETOZOA 



modified and often distorted by factors which resist the surface 

 tension of the plasm, we will analyse the genera of the group, 

 in order to weigh the influence of these factors and trace their 

 distribution. This we can do by adopting the following con- 

 ventional figures as representing typical forms, with inter- 

 mediate connections, and grouping around these conventional 

 figures the natural forms approximating thereto. 



B 



Fig. 1. 



It will be seen that A and C are depressed and elevated varia- 

 tions of B ; that D and E are stalked varieties of B and C ; and 

 that F is E much elongated. 



A. Depressed Forms. — These mainly illustrate the effects of 

 gravitation and low surface tension. Depressed symmetrical 

 forms are either simple sporangia or cushion-like structures con- 

 sisting of confluent sporangia combined into what is called an 

 acthalium. Other and unsymmetrical forms spread on the 

 substratum with an irregular outline. They are known as 

 plasmodiocarps and are often much distorted. The majority of 

 the sixteen genera of the Calcarineae present these flattened or 

 irregular forms, owing to the quantity of lime (calcium car- 

 bonate) which their plasm contains. Of the thirty-two other 



