38 THE MYCETOZOA 



THE plasmodial and the spore-bearing phases in the life-history of 

 the Mycetozoa have long been known. Many of the generic names 

 date from the eighteenth century, and Fries enumerated 192 

 species in 1829. 



By the earlier naturalists these organisms were classed, under 

 the names Myxogastres or Myxamycetes, with the Gasteromycetous 

 Fungi, to which the sporangia of the Endosporeae present in 

 miniature a considerable superficial resemblance. Although this 

 view of their relationship is now generally abandoned, its influence 

 may be traced in the names " capillitium " and " hypothallus " 

 which are still applied to structures present in the spore-bearing 

 stages of the Mycetozoa. 



It was de Bary (1-3) who first worked out (1859-64) the main 

 features of the life-history, showing that the spore hatches out as 

 a naked protoplasmic body which assumes a flagellate form, that 

 this passes after successive divisions into an amoeboid form, and 

 that from the amoebae the large plasmodia arise. 



Cienkowski (7) contributed (in 1863) the important observation 

 of the mode of origin of the plasmodia by the fusion of the 

 amoeboid swarm-cells. 



De Bary showed how widely different, both morphologically 

 and physiologically, these organisms are, not only from the higher 

 fungi, but from all those included in the vegetable kingdom, and 

 clearly expressed the opinion that they should be regarded as 

 animals. 



In the discussion of the relationships of the Mycetozoa which 

 followed the publication of de Bary's work, it w r as early recognised 

 that some of the simple organisms included in the large and ill- 

 defined group of the Monadina present phases comparable with those 

 of the Mycetozoa. Thus Protomonas amyli and 'P. parasitica, which 

 are parasitic in vegetable tissues containing starch, were found 

 by Cienkowski (8) to begin their development as flagellate swarm- 

 cells, and then to become amoeboid, in which stage they take in 

 or envelop starch grains, which they are able to digest. Later they 

 encyst ; the protoplasm withdraws from the undigested food and 

 breaks up into a fresh brood of swarm-cells. Moreover, fusion of 

 several individuals may occur in the amoeboid stage prior to 

 encystment. An encysted resting stage is also found in the life- 

 history. 



With the object of introducing order into the heterogeneous 

 assemblage of organisms which were, at the time of writing, classed 

 as Monadina, Cienkowski proposed (5) to restrict this name to forms 

 which passed through a life - history approximating to that of 

 Protomonas. 



The group, as thus limited, was regarded by him (8) as inter- 

 mediate between animals and plants, and presenting affinities in 



