THE PROTOZOAN SUBGROUPS 347 



from the flock, either keeping them isolated or kilUng and burning them. 

 It is better to put all of the chickens on new ground if possible, other- 

 wise the ground should be covered with lime and spaded so that it may 

 be exposed to the drying effect of the sim and air. All litter and nesting 

 should be burned and a thorough cleaning up of the quarters followed 

 by the application of a strong disinfectant solution. After drying, 

 the floors may be protected from recontamination somewhat by covering 

 them with shavings, chopped bedding, or other absorbant material, 

 which is to be cleaned up and burned daily. Boards should be placed 

 beneath the roosts to receive the droppings for convenient daily removal. 

 Contamination of feeding and drinking vessels can in a measure be pre- 

 vented by elevating them somewhat from the ground. They should at 

 all times be kept clean; daily treatment with scalding water or flaming 

 followed by exposure to the sun will do much to eliminate the source 

 of the infection. 



Order II. Hemosporidia 



Sporozoa (p. 336). — ^The Hemosporidia are Sporozoa which dwell in 

 the blood where they invade the corpuscles, hence are cytozoic. Flag- 

 ellated stages appear in their life history, and many protozoologists 

 suspect that the entire group has been evolved from the flagellated 

 Protozoa. Comparing the life history of the malaria organisms (p. 318) 

 with that of the Coccidia (p. 337) a distinct difference will be noted in 

 the method of infection, the hemosporidian, as is true of others of the 

 group, being transmitted from the blood of one animal to that of an- 

 other by means of a known intermediate host, while the Coccidia infect 

 directly, usually by food or water bearing the cysts. In diseases caused, 

 by Hemosporidia, the infection,, due to the activities of the intermediate 

 host, is more widely disseminated, and large numbers of animals may 

 be seriously and fatally attacked. As blood parasites, therefore, the 

 Hemosporidia may be rated with the trypanosomes in pathologic im- 

 portance. 



Texas Fever 



Tick fever. Splenic fever. 



Smith and Kilbourne in 1893 found small parasites in the red blood 

 corpuscles of cattle suffering with Texas fever. Due to their frequent 

 occurrence in pairs, they were given the specific name bigeminum, and the 

 genus was named Pyrosoma. The later generic name Piroplasma was 

 derived from their often assumiag a pear-like form, and the name now 

 generally used for the hemosporidian causing Texas fever is Piroplasma 

 bigeminum (Fig. 171). 



The medium by which the organism is transmitted is the cattle tick 

 Margaropus annulatus, which crawls upon its host as a larva, attaches, 



