102 



GENERAL BIOLOGY 



divide and become very numerous, but there is no dis- 

 tinction of cells. A plasmodium may become divided 

 by the flowing apart of its mass in divergent direc- 

 tions, or two plasmodia may meet and wholly coal- 

 esce. They possess little individuality. 



Dry weather checks the growth of the plasmodia and 

 often initiates the reproductive phase of the life of the slime 



molds, in which they re- 

 semble plants. The plas- 

 modia then abandon the 

 darkness and creep out upon 

 the exposed surfaces of the 

 log or stump, or a little way 

 up the stems of nearby 

 plants. They develop cell 

 walls about all their nuclei 

 and these walls are compos- 

 ed of a characteristically 

 vegetable substance, cellu- 

 lose. Their most elevated 

 portions develop sporangia 

 of various and often beauti- 

 ful forms. These contain 

 multitudes of spores. This 

 maturing process takes place 



FIG. 59. Slime molds in spore bearing verV QUicklV a few daVS 



stage, a, Trichia; b, Stemonitis. J ^ * 



or even hours may be 



sufficient ; it is to be sought on the bright and sunshiny days 

 that follow summer showers. 



The spores are scattered with the bursting of the spor- 

 angia at maturity. In some of the commoner slime molds 

 (fig- 59)> they are assisted in making their exit by the 

 movements of certain spirally twisted threads (capillitial 

 threads: collectively the capillitium) which occur in the 





