36 PRACTICAL PAKASITOLOGY 



authentic cases of human infection by Sarcosporides (one case in 

 Egypt, that of a Sudanese, two cases in France), the particular para- 

 site would appear to have been Sarcocystis tenella. Otherwise, it is 

 customary to distinguish the species of Sarcosporides by giving them 

 the names of their hosts. In addition to the varieties already men- 

 tioned, the following have a practical interest : 



(1) S. bertrami, Dofl. Found in the muscles of the horse, 

 especially in those of the throat and neck. Siedamgrotzky found 

 it in all the horses which he examined for it in Dresden. Many 

 veterinary ' authorities believe that the so-called "ice-ball swellings" 

 (Eisballengeschwiilste) of horses are due to the presence of this 

 variety of Sarcosporide, the young spores migrating into the neigh- 

 bouring tissues after the bursting of the sac. There is, however, no 

 definite grounds for this belief, as such a developmental stage does 

 not approximate to any detail in the life-history of other and better 

 known Sarcosporides. 



(2) S. blanchardi, Dofl. Found in the muscles of the ox and 

 the Java buffalo. According to Sanfelice, it is present in the tongue 

 of nearly all Sicilian cattle. 



(3) S. muris (K. BL). Found in the rump muscles of the 

 house-mouse and the common rat. Remarkable for the length 

 (several centimetres) which individuals sometimes attain. It differs 

 from S. tenella in that it does not completely destroy the muscle- 

 fibre in which it occurs. The parasite has, however, a special signifi- 

 cance ; .Koch and Smith found it possible to bring about an 

 artificial infection of mice by feeding them with Sarcosporides. 

 Negri 1 believes that he has observed reproduction of S. muris, as of 

 S. bertrami, by simple binary fission lengthwise of the spore. 



Class III. Flagellata. 



The Flagellates, or whip-cells, are distinguished by the possession 

 of one or more flagella. These organisms are particularly important as 

 being the originators of a number of very dangerous diseases. Unlike 

 the Amoebae, little is to be gained by the examination of free-living 

 forms, the difficulty of obtaining material outweighing any advantage 

 to be derived from their study. 



Before entering into a description of the various species of 

 Flagellates, it is advisable to consider the characteristics of their 

 flagellate apparatus. This may assume various forms, the most 

 important being as follows : 



'A. Negri, "Beobachtungen ueber Sarcosporidien," Centralbl. f. Bakt., &c., 

 part i, No. 47, 1908, pp. 56-61. 



