glands are enlarged and haemorrhagic ; (3) Infarcts 



occur in the liver, lungs and kidneys. These changes 



are mainly due to injury caused by the collection of 



large masses of parasites. 



Transmission. (i) The disease is not transmissible 



by inoculation. Eu. appendiculatus, the brown tick ; 



and Eu. simuf are known carriers. Larvae which have 



fed on infected animals transmit the disease in the 



nymphal stage only. Nymphs which have fed on 



infected animals transmit in the adult stage only. 



The transmission is accordingly not hereditary. The 



blood of recovered animals is not infective as in the 



case of P. bigeminum. 



Life history of Eu. appendiculatus with three hosts, 



i.e., changes after the larval and nymphal stage. 



Eggs on grass, According to tempera- 



hatch in ture and moisture ... 28 days. 



Larvae remain on 

 grass till they 

 find a host. 



On cattle. Host No. I. Take in- 



fection ... ... 3-4 days. 



On grass. Dormant, first moult 



takes place ... ... 21 days. 



Nymphs on cattle. Host No. II. Give in- 

 fection and take infec- 

 tion ... 3-4 days. 



On grass. Dormant, second moult 



takes place ... ... 18 days. 



Adults on grass. 



On cattle. Host No. III. Give in- 



fection. Copulation. 

 ? drops off ... ... 4 days. 



? on grass. Egg-laying begins in ... 6 days. 



(Some thousands laid.) 



