488 Diseases 0/ the Genital Organs 



of cows in a herd have aborted, it is meant that someone has 

 observed one-fifth of the females expel fetal cadavers. Many 

 more embryonic or fetal cadavers may have been expelled 

 unseen, or very small embryos may have become macerated 

 and absorbed, but these are not included. In this sense 

 "abortion" has acquired a preeminent place in veterinary 

 science and the phenomenon is commonly regarded as a 

 specific disease. 



(a) Tin- history of abortion is extensive. Its occurrence 

 has been noted by biblical and other early writers and was 

 frequently recorded in medieval times. The occurrence of 

 abortion has generally caused greatest concern in cattle be- 

 cause, since their milk and meat have occupied a preeminent 

 place in the food supply of most nations, any interference 

 with this supply imperils human life and health. Perhaps 

 the phenomenon has occurred more frequently in cattle than 

 in other domestic animals because the conditions favoring 

 it have been most prominent in cattle. Abortion has been 

 noted most in highly civilized countries with dense popula- 

 tions where milk and its derivatives are most highly prized, 

 and where any interruption of dairying causes a serious 

 shortage in this highly important human food. Since, where 

 a regular daily supply is demanded, for economic reasons no 

 surplus cattle are kept, any serious disturbance with milk 

 production is immediately felt. With the advancement of 

 civilization and concentration of population, the ratio of 

 milk- and meat-producing animals to the population becomes 

 less and higher efficiency of each individual animal becomes 

 < ssential. This increases the strain upon the animals, and 

 the diseases interfering with reproduction become more in- 

 tense. Accordingly abortion and other interferences with 

 reproduction are of ever-increasing importance to the state 

 and call for vigorous measures of control. 



At first abortion was frequently attributed to unfavorable 

 weather, such as unusual dampness or dryness, to bad food, 

 to emanations from swamps, and to accident. In early his- 

 tory only a few diseases, such as leprosy, were attributed 

 to contact. The belief in contact as a cause of disease ad- 



