43 SPECIFIC MICRO-ORGANISMS 



was proved for any blood-sucking invertebrate. The details of 

 the life cycle in the tick are unknown. It is certain however 

 that the infection is conveyed to the next generation of ticks 

 through the eggs and that these young ticks are capable of in- 

 fecting cattle. Renewed investigation of the parasite is much to 

 be desired. 



Texas fever is a very important disease of cattle in the southern 

 United States and a similar disease occurs in Europe, Africa and 

 South America. Young cattle usually survive the disease and 

 become immune. Older cattle imported into the endemic area 

 contract Texas fever and usually die of it. Immunity may be 

 conferred by injecting blood which contains a small number of 

 parasites, taken from an animal which has passed the acute stage 

 of the disease. Restriction of the Texas-fever area in the United 

 States is slowly progressing as a result of systematic eradication 

 of the tick. 



Babesia Canis. This organism occurs in the blood of dogs 

 suffering from the so-called malignant jaundice, and has been 

 carefully studied by modern methods by Nuttall and Graham- 

 Smith and later by Breinl 1 and Hindle. In morphology and life 

 history it agrees with B. bigemina as far as these have been worked 

 out, but B. canis is incapable of infecting cattle. The infection 

 is transmitted to dogs by several different species of ticks. 



Gregarina Blattarum. This organism lives as a parasite in 

 the intestine of the common cockroach Periplaneta orientalis, and 

 is therefore liable to be found in human food, and at times in 

 specimens from human cases submitted to microscopic study, 

 probably because of accidental presence of cockroaches in the 

 containers employed. The vegetative cells are elongated, often 

 attached together. The spore cyst results from the union of two 

 cells and the subsequent repeated division of the fertilized cell 

 to produce an enormous number of spores. These spores are 

 discharged from the cyst when it enters a fluid medium. When 

 fully developed, each spore contains eight sporozoits. 



1 Ann. Trap. Med. and Parasitol., Vol. II., pp. 233-248. 



