• MYCETOZOA 185 



These cysts may live as long as three years. Upon the re- 

 turn of favorable conditions, such as the addition of water to 

 the preparation, the contents of the sclerotia germinate, fuse 

 together, and thus again produce plasmodia {c-e). 



When lack of food material occurs, the Plasmodium under- 

 goes changes and develops sporangia. The first indication of 

 this process is the appearance of lobular masses of protoplasm 

 in various parts of the body (g). These masses are at first con- 

 nected with the streaming protoplasmic thickenings, but later 

 become completely segregated into young sporangia. During the 

 course of the formation of the sporangium, foreign bodies are 

 thrown out of the body, and around each sporangium there is 

 secreted a wall which, when mature, possesses a wrinkled ap- 

 pearance {h). The wall continues down to the substratum as a 

 slender stalk of varying length, and in many genera the end of a 

 stalk spreads into a network over the substratum, which forms 

 the base for the stalk. This base is known as the hypothallus. 

 \\'ith the external changes as outlined above, the interior of the 

 sporangium becomes penetrated by an anastomosing network of 

 flat bands which are continuous with the outer covering. This is 

 called the capillitium {i). 



Soon after the differentiation of these protective and sup- 

 porting structures, the nuclei divide simultaneously by mitosis 

 and the cytoplasm breaks up, directly or indirectly, into as 

 many small bodies as there are nuclei. These uninucleate bodies 

 are the spores which measure about 3 to 20 microns in diameter 

 and which soon become covered by a more or less thick mem- 

 brane (j), variously colored in different species. The membrane 

 seems to be composed of cellulose. 



The mature sporangium breaks open, sooner or later, and the 

 spores are carried, and scattered, by the wind. When a spore 

 falls into the water, its membrane ruptures, and the protoplas- 

 mic contents emerge as an amoebula {k, I). The amoebula 

 possesses a single vesicular nucleus and contractile vacuoles, and 

 undergoes a typical amoeboid movement. It assumes an elon- 

 gated form and protrudes a flagellum from the nucleated end, 

 thus forming a myxoflagellate (zoospore, swarmer) (m, «), which 

 undergoes a peculiar dancing movement and is capable of form- 

 ing short and pointed pseudopodia from the posterior end. It 



