INTRODUCTION 



Fries gave the name of Myxogastres, in 1829, to the group of 

 organisms described in this Monograph, placing it among the 

 Gasteromycetous Fungi. In 1833 Wallroth substituted the 

 term Myxomycetes (Schleimpilze) for the older name, and this 

 came to be the generally accepted designation. Later in- 

 vestigations showed that the spores, instead of producing 

 a mycelium, as in the case of fungi, give birth to swarm-cells, 

 which coalesce to form a plasmodium. In consequence of 

 this discovery, which indicated a relationship with the lower 

 forms of animal life, de Bary in 1858 introduced the name 

 Mycetozoa. 



Under the head of Mycetozoa, de Bary still retained the 

 term Myxomycetes for the section so named by Wallroth, 

 but linked with it the Acrasieae of Van Tieghem {Sorophora 

 Zopf), a small group inhabiting the excrement of animals. 

 In these the spores produce swarm-cells, which multiply by 

 division but do not pass through a flagellate stage or coalesce 

 to form a plasmodium. At a certain period, when the fruits 

 are about to be formed, the swarm-cells approach each other 

 and adhere loosely in branching strings ; they eventually 

 concentrate at various points, becoming massed together in 

 aggregations of more or less definite shape ; the swarm-cells, 

 however, do not lose their individuality. In Dictyostelium 

 and some other genera of the Acrasieae, a stalk is formed by 

 the arrangement of a number of individuals in vertical rows in 

 the centre of the heap ; the surrounding amoeboid bodies creep 

 up this stalk and form a cluster at the extremity, where each 

 amoeboid swarm-cell acquires a spore-wall ; the spore-cluster 

 is not enclosed by a definite sporangium- wall. 



Rostafinsk' followed de Bary in the view that the formation 

 of a plasmodium indicates a wide separation in the natural 

 position of the Myxomycetes from the fungi, but he suppressed 

 that name entirely, adopting de Bary's class name Mycetozoa 

 in its place ; at the same time, he admitted into his Monograph 



