ANIMAL PARASITES 



S)\ 



arc filled with rounded cells, the pansporoblasts, from which the 

 spores are developed. The enveloping membrane is regarded by 

 some workers as derived wholly from the sarcoplasm of the 

 infected muscle fiber. In favorable preparations there may be 

 distinguished three layers: a delicate internal layer which passes 

 inward to form the walls of the chambers, a compact middle 

 layer, and a broad external layer (see Fig. 29). 



Search your preparation for young stages of the parasite in 

 the still distinctly recognizable muscle fiber. 



Cnidosporidia. — In the superorder Cnidosporidia are placed 

 Sporozoa infecting chiefly invertebrates and cold-blooded verte- 



Fig. 30. — A myxosporidian, Leptotheca ohlmacheri, from the kidney of the 

 frog. .4, spore; B, emerging amcebula; C, amaebula whose nuclei are undergoing 

 fusion; D, trophozoite containing two spores. (After Kudo.) 



brates, which are peculiar in that spore formation takes place in 

 the trophozoite while it is still growing. Still more characteristic 

 is the fact that the spores possess one or more peculiar bodies 

 known as polar capsules. Within these capsules there is an 

 elongate polar filament which is extruded when the spore is 

 taken into a new host and presumably serves to anchor it while 

 the amoeboid organism of the spore makes its way into the tissues. 

 Note the available demonstration specimens. 



References 



Alexeieff, A., 1913. Recherches sur les Sarcosporidies. Arch. tool, 

 exper., 51: 521-569. 



Kudo, R., 1919. Studies on Myxosporidia. A synopsis of genera and 

 species of Myxosporidia. Illinois Biol. Monographs, 5 (3-4), 265 pp. 



Kudo, R., 1924. A biologic and taxonomic study of the Microsporidia. 

 Illinois Biol. Monographs, 9 (2-3), 268 pp. 



Scott, J. W., and E. C. O'Roke, 1920. Sarcocystis tenella. Univ. Wyom- 

 ing Agr. Exp. Sta., Bvll., 124: 69-94. 



Smith, T., 1901. The production of sarcosporidiosis in the mouse by feeding 

 infected muscular tissue. Jour. Exptl. Med., 6: 1-21 



