SOUTHERN FEVER 263 



of the kidney had the same peculiar yellow colour already described. 

 The bladder was usually distended with bloody urine, and in such cases 

 the mucosa was more or less congested. The lungs in some cases were 

 emphysematous, in others a broncho-pneumonia was present. Again, 

 some, in fact all, presented a more or less hypostatic pneumonia, due to 

 weakness of the heart and kidney complications. Pleurisy was also 

 present in some cases. The pericardium was studded with petechise ; the 

 fat around the heart exhibited the same peculiar colour already mentioned. 

 Serous infiltrations and haemorrhages were sometimes found beneath the 

 skin of the lower jaw and neck. 



Mode of Infection. A ccording to Smith and Kilborne the natural 

 infection is caused by the blood-sucking tick (Ixodes or Boophilus bovis) 

 which lives on the skin of the cattle, in an enzootic territory becoming 

 charged with the parasite. 



The mature female tick on the animal's body has an oblong, oval- 

 shaped body, and somewhat resembles a castor-oil bean ; it presents a 

 dull leaden colour, is rarely more than J an inch long, and -f$ of an inch 

 in breadth, possessing four pairs of legs, situated on the antero-lateral 

 portion of the body. It attaches itself to its host by what is known as 

 the rostrum, in the centre of which is a barbed dart furnished on either 

 side with several rows of teeth arranged obliquely, which enable the 

 tick to adhere more securely to the skin. The male tick is usually 

 found attached to the skin immediately underneath the anterior portion 

 of the female, the body being of a dark brown colour and triangular in 

 shape. When fully grown it is very much smaller than the fully 

 developed female, and never being in an engorged condition, is much 

 more active and stronger in comparison with the female. As the female 

 tick engorges herself she is fecundated by the male, and at maturity 

 withdraws the barbed mouth organs or rostrum, falls to the ground, lays 

 a great number of eggs, shrivels up gradually and perishes. The para- 

 site is carried over in the eggs, and in from two to six weeks the young 

 ticks are hatched, creep upon the cattle, and infect them with the 

 disease. By this means fresh cattle arriving in infected districts 

 become affected, while the native cattle exhibit no diseased symptoms. 

 It is possible that they were infected as calves, and since then continued 

 to harbour the blood parasites ; in fact, inoculation of the blood of such 

 animals produces the infection in other cattle in regions where the 

 disease does not exist. Cattle travelling from infected regions can 

 infect healthy pastures, not by direct infection, but in a round-about 

 manner. The ticks that the cattle bring with them fall from the 

 animals and deposit their eggs on the ground, and the young ticks 

 infect the previously healthy cattle, the disease breaking out in forty- 

 five to sixty days after the appearance of the infected cattle, because 

 so much time must elapse before the young brood of ticks is capable of 



