CATTLE PLAGUE. 141 



vessels, men, dogs, conveyances ; in fact, by any material con- 

 taminated by a diseased animal. The contagium is destroyed by 

 dry air, by a temperature of about 140° F., by chlorine, car- 

 bolic acid, &c., and, it is stated, by putrefaction. Its virulence 

 is greatest at the outset of an outbreak. 



The fever, as shown by the elevation of the temperature, 

 begins when the poison has infected the whole mass of blood, or 

 within from about forty to sixty hours after its first entrance 

 into the system. Coincident with the elevation of temperature, 

 the chemical changes in the body are augmented, and, according 

 to Dr. Marcet, one of the products of degradation of tissue — the 

 urea — is largely increased. Soon afterwards the blood is other- 

 wise altered, the amount of fibrin largely increased, the amount 

 of water lessened, and the physical condition of the albumen 

 altered ; and, according to Dr. Beale, the proportion of soluble 

 substances is also largely increased. 



About the third or fourth day local congestions are to be seen 

 on the skin and visible mucous membranes, varying in intensity 

 and in size. Stagnation takes place in the small capillaries of 

 many parts of the body, the blood in which becomes coagulated. 

 A great increase of granular matter is found to occur both 

 within and without the vessels of the congested parts. The 

 capillaries become greatly enlarged, and the spaces between 

 them lessened or obliterated. At the same time considerable 

 nutritiv^e alterations take place in the mucous membrane and 

 skin, leading to very rapid and imperfect growth of many of 

 the cellular elements, and followed by rapid disintegration and 

 detachment in the form of discharges. As that portion of 

 the mucous membrane which is most essential for digestion is 

 most affected, the appetite soon fails, rumination ceases, and 

 large accumulations of undigested food are met with in the first 

 stomach. In many cases the villi of the small intestines are so 

 destro}ed, that even if food were taken it would scarcely be 

 absorbed in sufficient quantity to maintain life, and hence the 

 rapid exhaustion, failure of the heart's action, depression of 

 the animal heat, and general sinking of the powers. In some 

 cases, when the process is more superficial, the membrane 

 rapidly recovers its healthy condition ; and it is curious to find 

 that one affected part may be healing while another is just 

 beginning to suffer. 



