xvii DOUBTFUL FORMS 181 



easily overcome may be seen from the fact that both genera 

 are claimed at the present day both by zoologists and by 

 botanists. For instance, Prof. Huxley considered Haema- 

 tococcus as a plant, and expressed doubts about Euglena ; 

 Mr. Saville Kent ranks Haematococcus as a plant and 

 Euglena as an animal ; Prof. Sachs and Mr. Thiselton 

 Dyer place both genera in the vegetable kingdom ; while 

 Profs. Ray Lankester and Biitschli group them both among 

 animals. 



In Heteromita the only cell-wall is the delicate cuticle, 

 which in the zygote is firm enough to hold the spores up to 

 the moment of their escape : food is taken exclusively by 

 absorption, and nutrition is wholly saprophytic : there is a 

 contractile vacuole, and the movements are ciliary. 



Here again the characters are conflicting : the probable 

 absence of cellulose, the contractile vacuole, and the cilia 

 all have an " animal " look, but the mode of nutrition is 

 that of a fungus. 



In Protomyxa there is a decided preponderance of animal 

 characteristics ingestion of living prey, and both amoeboid 

 and ciliary movements. There is no chlorophyll, and the 

 composition of the cell-wall is not known. 



In the Mycetozoa, the life-history of which so closely 

 resembles that of Protomyxa, the cyst in the resting stage 

 consists of cellulose, and- so does the cell-wall of the spore : 

 nutrition is holozoic, a contractile vacuole is present in the 

 flagellulae, and both amoeboid and ciliary movements are 

 performed. Here again we have a puzzling combination of 

 animal and vegetable characters, and as a consequence we 

 find these organisms included among plants under the 

 name of Myxomycetes or " slime-fungi " by Sachs and 

 Goebel, while De Bary, Biitschli, and Ray Lankester place 

 them in the animal kingdom. 



