BOVINE PIROPLASMOSIS. 423 



days. The temperature, which may previously have risen to above 

 105° Fahr., suddenly falls, indicating the approach of death. 



If an immediate autopsy is made, the spleen is always found to 

 be enlarged, the intestinal mucous membrane reddish in tint or blood- 

 stained, and the serous membranes, particularly the endocardium, 

 covered with petechi^e. 



Few or no parasites can be discovered except in the blood from 

 the cardiac muscle and the kidneys. 



The grave form may end in recovery. This end is indicated by 

 the temperature remaining normal after defervescence, the appearance 

 of haemaphaeic icterus of an obstinate character, and the progressive 

 return of appetite. 



The disease is usually tran^^mitted by adult and larval ticks carrying 

 the parasite from infected animals. Lignieres has proved that this 

 transmission occurs through the medium of passive spores, which, 

 though themselves incapable of producing the disease, become active 

 and infective in consequence of the local irritation produced by the 

 poisonous saliva of the ticks. 



The pathogeny of Texas fever may be shortly summed up as 

 follows : — Animals suffering from the disease carry in their blood a 

 protozoan organism called the Piroplasma bigeminum, analogous to the 

 parasite of human malaria; once introduced into the blood, this 

 organism remains there in an active condition throughout the animal's 

 life ; it is transferred to susceptible cattle either within or without the 

 infected district by the Southern (U.S.) cattle tick Boophilus anmilatus ; 

 Southern cattle, although carrying the protozoa, are harmless unless 

 infested by this particular tick : the mature ticks and their eggs con- 

 tain the protozoa, and the mystery of certain grounds over which 

 infected animals have passed being first dangerous, then harmless, 

 and again dangerous depends on — {a) the infestation of the ground 

 with mature infected ticks ; (6) the destruction or death of the mature 

 ticks ; and (c) the hatching out of new (infected) ticks from the eggs 

 laid on the ground by the mature female ticks. 



Dr. Salmon states that in Texas a successful method of protection 

 is in practice based on the observations that young cattle do not 

 suffer so severely as adults, and that the disease always assumes a 

 milder form in winter. Young animals introduced during the winter 

 are inoculated with virulent blood. They contract a mild form of 

 disease, and afterwards resist. In this way the losses, which previously 

 amounted to 90 per cent, of all freshly introduced stock, have been 

 reduced to about 10 per cent. 



A remarkable and very interesting observation (if absolutely reliable) 

 deserves to be mentioned, viz., that the ticks develop regularly in the 



