CLASSIFICATION AXD GENERAL CHARACTERISTICS 471 



adult amoebae. In one species, after division of the nucleus and proto- 

 plasm, the daughter-cells become "swarm spores" with two flagella. 

 A certain form of conjugation has been observed in some varieties. 



Amoeba- are found mostly in standing fresh water and sea-water and 

 on moist vegetable substances. A few have been described in the body 

 fluids of the higher animals. Those so far known to be parasitic for 

 man are amoeba coli and a few closely related varieties which are 

 described below. 



FIG. 140 



A. Cell of root of cabbage infiltrated with plasmodiophora amoebae. The amoebae are fusing, form- 

 ing plasmodia. B. Beginning mitotic division of the amoebae. The nucleus of the host cell beneath. 

 (After Nawaschin.) 



The Mycetozoa are a group of organisms showing characteristics of 

 both plants and animals. They are, therefore, claimed by botanists as 

 well as zoologists. They have possessed some interest of late from a 

 medical standpoint because one variety, the plasmodiophora brassicae 

 Waronin (Figs. 140 and 141), which is an intra cellular parasite of mem- 

 bers of the cruciferse, producing large tumors in their roots ("fingers 

 and toes," "club-foot"), has been shown to form cell inclusions 

 somewhat similar to some of the cell inclusions seen in the carci- 

 nomata, and certain investigators have thought that it bears a re- 

 lation to the etiology of carcinoma. But so far no relationship has 

 been proven. The plasmodiophora brassicae, when inoculated into 

 experimental animals, produces only small granulomata which finally 

 disappear. 



