130 Veterinary Medicine. 



octopod nymphse and young males. After one week more on 

 the calf the nymphas moult a second time and become sexually 

 mature females. After fertilization the mature female increases 

 slowly for nineteen to twenty-two days, then very rapidly for a 

 few days longer, when she drops off from her host, and in two or 

 three days begins to lay eggs. Each blood-fed female lays on an 

 average 2100 eggs. 



Hosts. This tick attacks cattle and deer, and less frequently 

 horses. It is found on cattle where the skin is thin and tender, 

 on the inner sides of the thighs and elbows, on the pubis peri- 

 neum, udder and scrotum, and less numerously on other parts 

 (ears, neck, ribs, back). When abundant on the pastures, in 

 the comparative absence of cattle, it is alleged to attack horses, 

 especially about the ears, but clearer evidence is necessary as to 

 the identity of the parasite taken from the horse. 



Pathogenesis. In all cases these ticks cause local irritation 

 and swelling on their hosts. They open the way for the intro- 

 duction of many infections, but above all and most important of 

 all, they are the bearers of the piroplasma bigeminum which they 

 implant in their bites causing the protozoan cattle fever of our 

 southern states (See Texas Fever, Vol. IV). The natural pro- 

 ducts of the tick do not cause Texas fever, in districts into which 

 the piroplasma has not penetrated, but wherever, the animals 

 infected with this protozoon are found these ticks are the natural 

 means of conveying it from animal to animal. The ticks are the 

 more redoubtable that the piroplasma is transmitted through 

 the eggs from the parent tick to the offspring of the next gener- 

 ation. 



BOOPHII.US AUSTRALIS : TEXAS FEVER TICK OF AUS- 

 TRAUA, INDIA, S. AMERICA, PORTO RICO AND 

 CUBA. SCRUB TICK. 



Characters of female and male. Dorsal shield smaller, lighter in color, 

 capitulum shorter, mandibles with each apophysis, inner and outer, triden- 

 tate, male with central chitinous caudal appendix. Hosts : cattle, deer, 

 horse. Pathogenesis : convey Texas fever to cattle in countries in which 

 the piroplasma is present. 



Female. — I/ike that or Boophilus Annulatus. Lateral contrac- 

 tion of the body opposite the stigmata is usually greater ; dorsal 



