MICROBIAL DISEASES OF MAN AND DOMESTIC ANIMALS 843 



are found normally in all Individuals of certain species, as for example, 

 the mouse. Since the bodies of this general appearance which occur 

 in normal animals are evidently to be regarded as nuclear material 

 certain investigators are inclined to doubt the parasitic nature of 

 Anaplasma. 



Sarcospoeidia (Balbiani) 



Different species of this order are frequent parasites of all the 

 domestic animals, of mice and, occasionally, of man. Mice are killed 

 by them and it is possible that they may produce ill effects in men and 

 domestic animals but no definite disease is associated with their 

 presence. Though they may occur in any part of the body, they are 

 most numerous in certain muscles, such as those of the larynx and 

 oesophagus, which are near the alimentary canal. For this reason it 

 seems possible that they may enter the bodies of their hosts with food, 

 but our knowledge of their life history is incomplete. 



Myxosporidia (Biitschli) 



There are many species in this group which are parasitic in fishes 

 and certain arthropods but not in higher animals. The classification 

 is based largely on the character of the spores produced. The latter 

 are provided with a resistant membrane or shell and with polar 

 capsules, each of which contains a coiled filament which when 

 extruded serves to anchor the spore to the surface. The spores are 

 produced continuously within the protoplasm of the mother organism 

 which may be situated in any part of the body of the host. Severe 

 infection with myxosporidia may cause boil-like lesions and the death 

 of large numbers of fishes. 



MicROSPORiDiA (Balbiani) 



Protozoa belonging to this order do not produce disease in man. 

 They are the cause of a disease of bees, and they are of particular interest 

 because one of them, Nosema bombyds, causes Pebrine, a serious disease 

 affecting silk- worms (page 656). 



Infusoria (Leddermiiller, 1763) 



Most of the parasitic infusoria occur in the alimentary tracts of 

 their hosts. Harmless infusoria are found in the stomachs of many 



