328 THE AMERICAN" MONTHLY [Nov 



an amoeba. The whole life of the organism in any case 

 must be taken into account. At the outset plants and 

 animals are alike ; there is no doubt about it ; they differ 

 in the course of their life histories. The plasmodium is 

 the vegetative phase of the Slime-mould. It needs on cell- 

 walls of cellulose, no more than do the dividing cells of a 

 lily-endosperm : both are nourished by organic food and 

 resort to walls only as conditions change. The possession 

 of walls is an indication of some maturity. In the Slime- 

 mould the assumption of walls is indeed delayed, but 

 merely delayed. Walls at length appear, and when they 

 do come they are like those of the lily; they are cellu- 

 lose. The Myxomycetes may be regarded as a section of 

 the organic world in which the forces of heredity are at 

 a maximum, whatever those forces may be. Slime-moulds 

 have in smallest degree responded to the stimulus of en- 

 vironment. They have, it is true, escaped the sea, the 

 fresh waters in part, and become adapted to habitation on 

 dry land ; but nothing more. 



About 400 species of Slime-moulds have been described. 

 Saccardo enumerates 443, inclusive of those denominated 

 doubtful or less perfectly known. These 443 species are 

 distributed among 47 genera, of which 15 are represent- 

 ed by but a single species each, — monotypic. In the United 

 States there have been recognized about 200 species. Of 

 those here described, some are almost world-wide in their 

 distribution, others are limited to comparatively narrow 

 boundaries. The greater number occur in the temperate 

 regions of the earth, although many are reported from 

 the tropics, and some even from the arctic zone. 



If the Plasmodium malarice be indeed called a Slime- 

 mould, and be, as is alleged, the promoting cause and 

 agent in malarial fever, then the group entire suddenly 

 springs to most unusual interest in the attention of all 

 mankind. Aside from the injurious tendencies possible 

 or real of these two, I know not that all other Slime- 



