2 THE NORTH AMERICAN SLIME-MOULDS 



to designate the vegetative phase in any species, as the 

 plasmodium of the species. It was formerly taught that 

 the plasmodium is unicellular, but more recent investigation 

 has shown that the plasmodial protoplasm is not only multi- 

 nuclear but karyokinetic ; its cells divide and redivide, as do 

 the reproductive cells of plants and animals generally. Never- 

 theless, in its plasmodial phase, the Slime-mould is hardly to 

 be distinguished from any other protoplasmic mass, may be 

 compared to a giant amoeba, and justifies in so far the views of 

 those systematists who would remove the Slime-mould from the 

 domain of the botanist altogether, and call them animals. The 

 plasmodium is often quite large. It may frequently be found 

 covering with manifold ramifications and net-like sheets the 

 surface of some convenient substratum for the space of several 

 square feet. 



The substance- of the plasmodium has about the consistency 

 of the white of an egg ; is slippery to the touch, tasteless, and 

 odorless. Plasmodia vary in color in different species and at 

 different times in the same species. The prevailing tint is 

 yellow, but may be brown, orange, red, ruby-red, violet, in fact 

 anything but green. Young plasmodia in certain species are 

 colorless (Chondrio derma floriforme), many have a peculiar ecru 

 or creamy tint difficult to define. Not only does the color 

 change, sometimes more than once in the course of the life 

 history of the same species, but it may be the same for several 

 forms, which in fruit are singularly diverse indeed, so that 

 the mere color of the plasmodium brings small assistance to 

 the systematist. In fact, the color depends no doubt upon the 

 presence in the plasmodium of various matters, more or less 

 foreign, unassimilated, possibly some of them excretory, dif- 

 fering from day to day. In its plasmodial state, as has been 

 said, the Slime-mould affects damp or moist situations, and 

 is found during warm weather in humus, on piles of rotten 

 leaves, straw, but especially on and in the wet tissues of rotten 

 stumps and logs. In such a situation the protoplasm spreads 

 over all moist surfaces, creeps through the interstices of the 



