INSECT ENEMIES OF LIVE STOCK 167 



joined, and appear like two diminutive pears, joined by a 

 common stalk, or they may lie in opposite directions, and 

 sometimes they appear almost as a straight line ; the varied 

 shapes denote stages in their life-history. The micro- 

 organisms multiply by division, so that, at times, four of 

 them may be found in one blood corpuscle. All the time 

 the parasites are within a blood corpuscle they show 

 amoeboid movements, that is to say, they move about after 

 the fashion of an Amceba, a very diminutive and lowly 

 animal, resembling nothing so much as a tiny globule of 

 living jelly, and not only do they move, but they eventually 

 break up the blood corpuscle within which they have been 

 enclosed, setting free the red colouring matter which is 

 execreted with the urine. Normally, a cubic millimetre of 

 bovine blood contains some seven or eight million red- 

 blood corpuscles, but, in a severe attack of piroplasmosis, 

 the number may be reduced to below a million. Emacia- 

 tion, loss of appetite, and, eventually, coma and death may 

 follow these internal changes. 



In some parts of the United States, where Texas fever is 

 rife, the death-rate of cattle brought into the afflicted area 

 exceeds ninety per cent. When recovery takes place it is 

 very protracted, and sometimes development is permanently 

 arrested. Quite apart from the fact that they carry 

 disease, the ticks are a severe drain on the animal economy, 

 as the figures of the following experiment show. A steer, 

 badly attacked by ticks, was losing weight, so it was freed 

 of these animals by dipping, and weighed, turning the 

 scale at 730 Ibs. In two months' time the animal, still tick- 

 free, was weighed again, and scaled 1,015 Ibs., a gain of 

 285 Ibs. in two months, or 4| Ibs. a day. The feeding was 

 the same as before in quantity and quality, a fact that 

 shows clearly that a largely increased amount of food is 

 required by tick-infested cattle to make up for the loss 

 caused by the parasites ; flesh is put on slowly, or not at 

 all, and the milk production is greatly diminished. 



