4 THE NORTH AMERICAN SLIME-MOULDS 



arable size, and so await the return of favorable conditions 

 when former activity is quickly resumed. Sometimes the 

 larger plasmodia pass into the resting phase by undergoing a 

 very peculiar change of structure. In ordinary circumstances 

 the abundant free nuclei demonstrable in the plasmodium 

 afford the only evidence of cellular organization. In passing 

 now into the condition of rest, the whole protoplasmic mass 

 separates simultaneously into numerous definite polyhedral or 

 parenchymatous cells, each with a well-developed cellulose 

 wall. 1 When the conditions essential to activity are restored, 

 the walls disappear, the cellulose is resorbed, and the plas- 

 modium resumes its usual habit and structure. 



The plasmodial phase of the Slime-mould, like the hyphal 

 phase of the fungus, may continue a long time ; for months, 

 possibly for years. The reason for making the latter statement 

 will presently appear. But however long or short the plas- 

 modial phase continue, the time of fruit, the reproductive phase, 

 at length arrives. When this time comes, induced partly by a 

 certain maturity in the organism itself, partly no doubt by the 

 trend of external conditions, the plasmodium no longer as 

 before evades the light, but pushes to the surface, and appears 

 usually in some elevated or exposed position, the upper side of 

 the log, the top of the stump, the upper surface of its habitat, 

 whatever that may be ; or even leaves its nutrient base entirely 

 and finds lodging on some neighboring object. In such emer- 

 gency the stems and leaves of flowering plants are often made 

 to serve, and even fruits and flowers afford convenient resting 

 places. The object now to be attained is not the formation of 

 fruit alone, but likewise its speedy desiccation and the prompt 

 dispersal of the perfected spores. Nothing can be more 

 interesting than to watch the Slime-mould as its plasmodium 

 accomplishes this its last migration. If hitherto its habitat has 

 been the soft interior of a rotten log, it now begins to ooze out 

 in all directions, to well up through the crevices of the bark as 

 if pushed by some energy acting in the rear, to stream down 



1 De Bary, Morphology and Biology of the Fungi, p. 428. 



