I SPOROZOA 65 



The tick at length drops off the animal whose blood it has been sucking 

 and proceeds to deposit its eggs amongst the grass. These eggs, already 

 infected while in the body of the parent, develop into infected ticks 

 and these creep up on to grass blades and patiently wait for the oppor- 

 tunity of attaching themselves to an animal. Should this happen the 

 animal bitten is inoculated with the Babesia, which occurs in the salivary 

 glands of the infected tick in the form of swarms of " sporozoites." 

 The details of the life-cycle within the body of the tick which culmin- 

 ates in the formation of these sporozoites is not yet complete!}- worked 

 out. 



Besides the parasite of Texas Fever a number of other closely allied 

 species are known. In various parts of Europe a similar parasite has 

 been found in the blood of cattle and may be the same species. In South 

 Africa practically all cattle have in their blood B. mutans, while occasion- 

 ally a somewhat similar parasite — Theileria parva — causes destructive 

 epidemics [" East Coast Fever " — South and East Africa, Central Asia, 

 Japan, etc.]. Other species of Babesia occur in Dogs, Sheep, Horses, 

 Mice, and other mammals. A conspicuous feature of the disease (Piro- 

 plasmosis or Babesiosis) is the destruction of red blood-corpuscles and 

 the consequent passing away of the red colouring matter of the blood 

 in the urine (Haemoglobinuria), and it is further a general characteristic 

 that the transmission of the parasite is carried out through the agency 

 of Ticks, in the body of which the parasite goes through a complicated 

 and as yet not completely worked out cycle of developmental changes. 



B. Neosporidia 



The remaining members of the Sporozoa differ from those hitherto 

 mentioned in the feature that reproductive processes go on throughout 

 the period of active feeding and growth instead of being relegated to a 

 point in the life-history subsequent to this. They are hence grouped 

 together under the special heading Neosporidia. 



(4) Cnidosporidia. Under this heading are grouped together a 

 number of Sporozoa characterized by the fact that their spores possess 

 peculiar bodies known as polar capsules (Fig. 27). A polar capsule is a 

 pear-shaped hollow structure containing in its interior a spirally coiled 

 hollow filament which can be instantaneously shot out so as to perforate 

 any soft surface with which the spore is in contact and in this way anchor 

 it in position. The extrusion of the filament commonly takes place in 

 the alimentary canal of some animal that has swallowed the spore, and 

 the spore thus is held in position attached to the lining of the alimentary 



F 



