8 MYCOLOGY 



should be used. One of the strongest arguments is that if we consider 

 them as plants they belong to the phylum of the fungi and hence this 

 name Myxomycetes aligns itself with Schizomycetes and Eumycetes 

 generally adopted for the other groups of fungi. It conduces to clarity 

 and simplification of classification to adopt the name of Wallroth for 

 the class of organisms incapable of an independent existence, being 

 destitute of chlorophyll and mainly saprophytic. The older name is 

 retained, however, as the name of the third order of Myxomycetes, 

 hence there should be little criticism of the view taken above. The 

 Myxomycetes (Mycetozoa, Schleimpilze, Pilztiere, Slime Moulds) are 

 chlorophylless organisms. Their vegetative condition is known as a 

 Plasmodium which is a naked streaming mass of protoplasm. Repro- 

 duction is by means of spores produced as exospores, or endospores, 

 the latter in sporangia, aethaha, or plasmodiocarps. The spores give 

 rise to amoeboid cells or flagellate swarmers which unite later to form 

 the Plasmodium, or develop directly into the plasmodium. 



ORDER I. ACRASIALES.— The members of this order live on 

 the excrements of animals and on the decaying parts of plants. They 

 commence their development with the escape of an amoeboid body 

 from the walls of the spore and then move about by creeping move- 

 ments, never assuming cilia for locomotion. The amoeboid cells pile 

 up on one another without coalescing to form what has been called an 

 aggregate plasmodium, and they remain distinct, and artificially sepa- 

 rable, though closely packed together until the fructification forms, 

 when they rise above the substratum and form bodies of definite 

 shape. Every one, or the majority of these definitely arranged amoe- 

 boid bodies, becomes a spore covered by a deUcate membrane atid of an 

 average size of 5 to 10 /i. These heaps of spores resemble the sporangia 

 of the true slime moulds, but there is no distinct sporangial wall, 

 the spores being held together by a structureless enveloping substance. 

 The plants of this group are saprophytes. Guttulina rosea Uves on 

 decaying wood in Europe. Dictyostelium mucoroides is frequent on 

 old dung, while Acrasis granulata is found on old yeast cakes. Poly- 

 sphondylium violaceum occurs in southern Europe on manure. 



ORDER II. PHYTOMYXALES.— The slime moulds of this order 

 are parasites which Uve in the cells of higher plants. The plasmodium 

 is limited by the cell walls of the host plants, and has its origin in 

 amoeboid cells which enter and infest the host cells, resulting in a 



