74 PARASITOLOGY. 



rior extremity of the body, forming a mass number- 

 ing, usually, 4,000 to 5,000. These eggs hatch in 

 about three weeks, if the temperature is favorable. 

 The larvae are small, six-legged asexual parasites. 

 In this stage they have lived in a bottle for six 

 months without food. They crawl over the ground 

 or upon the blades of grass or weeds, and thus are 

 brushed off by animals passing along. Once on the 

 animal they attach themselves usually in the region 

 of the thigh, between the hind legs. After one week 

 they moult (passing through a change in the ana- 

 tomical structure, during which time they shed the 

 skin.) They are now provided with four pair of legs 

 and at the end of another week they moult again, 

 and become sexually mature. The males seek the 

 females and place themselves in apposition, in which 

 position the male can be found still alive after the 

 female is fully engorged. But its life is short after 

 being removed from the host ; it dies within a few 

 hours. The female draws blood slowly for the first 

 two weeks, then rapidly for the third week, becom- 

 ing fully engorged in three weeks, drops off, and is 

 ready to begin ovulation ; gradually shrinks during 

 ovulation until she is only about one third of her 

 original size, then dies. 



Condition Produced. — The tick carries the proto= 

 zoa (Piroplasma Bigeminum) causing Texas or 

 Splenic Fever. The larva, as soon as it gets onto 

 the host, attaches itself to the skin and begins to 

 draw blood. At this time it inoculates the host with 

 the protozoa. The single celled parasites enter the 

 red blood cells, break them up and liberate the hem- 

 oglobin; the protozoa have multiplied in sufficient 



