380 Veterinary Medicine. 



of the disease. In some the affection appears to be a purely local 

 one (American), the microbe being confined to the genital or 

 genito-urinary mucosa, whereas in others the microbes (Bangs', 

 Galtier's, etc.) livealso in the blood producing a general infection. 



Two great types at least have been demonstrated in Europe 

 and America. Whether future investigation shall show the 

 presence in one of these continents of the types as yet only known 

 in the other, remains to be seen. If the particular forms should 

 turn out to be limited to different continents we are at once con- 

 fronted with the necessity of an international sanitary quarantine, 

 and inspection. Matters are bad enough now in our dairying 

 districts, but if we are to be open to the importation of new types 

 of abortion, which do not mutually immunize against each other, 

 but which may be taken one after another in succession through 

 a series of years, they may easily become incomparably worse. 



Acquired Immunity. The question of persistent abortion year 

 after year, in the same animal, is most important. If a first con- 

 tagious abortion entails a second, a third, a fourth and a fifth 

 in the same animal, in as many successive years, then manifestly 

 the preservation of such animal is a most wasteful economy, al- 

 together independently of the danger of her transmitting the in- 

 fection to healthy stock. It, however, she herself becomes im- 

 mune after a first or second abortion, it may be profitable to retain 

 her for milk production or breeding, provided that she can no 

 longer infect susceptible cows with which she must come in con- 

 tact. 



Acquired immunity of the individual cow is the rule after one 

 or two abortions caused by the microbes with which we are at 

 present most familiar. There are exceptions to this rule due to 

 special nervousness and excitability of given cows, which tend 

 to an indefinite repetition of the abortion, under the stimulation 

 of pregnancy, of the continued presence of the microbe, or of 

 some local disease (tubercle, tumor, parasite, etc.) of the ovary, 

 womb or peritoneum. Yet statistics show that this only applies 

 to a small proportion of cows and these the most nervous and 

 excitable. The tendency toward insusceptibility to the deleterious 

 action of the germ, which may still be present, is in the cow as 

 a rule greater than the disposition toward a nervous encrease of 

 the susceptibility. The difficulty of reaching a conclusion on 



