DR. LEGEAR'S STOCK BOOK. 313 



"serum" method of treatment in Texas fever. It is true that 

 Texas fever is caused by an animal parasite (protozoon); while 

 in diphtheria, the cause is a vegetable parasite (bactera). This 

 difference in the nature of the cause of these two diseases, has 

 led most investigators to the belief that there must be a differ- 

 ence in the process by which immunity is acquired. But the 

 simple law of immunity will teach us that there can be no essen- 

 tial difference in the process by which immunity is acquired 

 against micro-organisms and poisons of any kind. Immunity 

 against Texas fever is certainly acquired, and is fully as effective 

 as that acquired against any of the bacterial diseases. In natur- 

 ally acquired immunity against Texas fever the ticks have taken 

 the place of the hypodermic syringe in the way of inoculation. 

 The animal may while young, if the dam is immune, gain im- 

 munity through the milk: and on Southern soil the ticks keep up 

 the natural inoculations from year to year by which immunity 

 from the disease is obtained. 



The serum used in this preventative treatment must be ob- 

 tained from a Texas steer or cow, or any other animal that has 

 had the disease and recovered, or is naturally immuned. It is in- 

 jected or inoculated by a hypodermic syringe under the skin of 

 the animal to be treated. This blood serum sets up a slow pro- 

 cess of disease in the animal, and after sufficient has been in- 

 jected to make the animal safe from an attack, the ticks that 

 infest her body from year to year afterwards continue to keep 

 the animal in a state of immunity. The serum is meant to tide 

 them over the acclimation period, and can be prepared and used 

 by any one having the apparatus and proper instruments. It 

 can be obtained at the Texas Experiment Station, where they 

 keep it on hand or prepare it fresh on short notice. 



