992 



ANATOMY AND PHYSIOI.OGY OF LIVESTOCK 



anatomy and 

 physiology: 

 generalities. 



action of the saliva tends to attenuate the virus, while, in the urine, its 

 virulence is long maintained unaltered (i), 



769 - Osmotic Equilibrium between Blood and Milk in the Cow. — \ ^vn der laan, f. it. 



in Biochcmisclu- Zcilschritt, \'ol. 73, Xos. 3-6, pp. 313-325. Berlin, April 4, iyi6. 



The writer's previous experiments (2), in relation to osmotic concen- 

 tration of the blood, milk and bile in the cow, have shown that the value of 

 the three concentrations is the same, even if the osmotic concentration of 

 the blood is artificially modified. These experiments, however, having all 

 been made with healthy animals, the concentration in sick animals still 

 remained to be studied. 



It has been ascertained that in man certain diseases, chiefly those of 

 the heart and kidneys, produce a great increase of osmotic pressure in the 

 blood, owing to derangements of metabolism. Doctors therefore ascertain 

 the freezing point of the blood of their patient when the}^ wish to find out 

 whether one of the kidneys or both are diseased. 



The wiiter used this method for studj'ing the osmotic concentration 

 of the blood in 8 cows suffering from : toxemia, constipation, chronic peri- 

 tonitis with acute anteritis, pyelonephritis, loss of blood through perforation 

 of the rectum, tuberculosis (2 cases), fracture of the ileum. With this object 

 he determined the freezing point of the blood, the milk, and in some cases the 

 bile. The investigations showed that the freezing point of the blood and 

 milk are not modified by the disease. In one case onlj^ the osmotic pressure 

 of the blood was increased owing to auto-intoxication, but the osmotic press- 

 ure of the milk had undergone a corresponding increase. The Author men- 

 tions in this connection an experiment made b^'^Pi.iESTERS on a cow suffering 

 from anthrax (splenic fever), which gave a similar result. 



In spite of the small number of cases observed, it is believed that 

 the diseased condition can only increase and never reduce the depression of 

 the freezing point of the blood of the cow. In most cases the disease will not 



(i) The question dealt with here is, as it were, the crux of the problem of immunity, not 

 only in respect to foot-and-mouth disease, but also to other infectious diseases \\ith filterable 

 virus located in the blood. Thus, for instance, in cow-pox just as in foot-and-mouth disease, 

 by passage through hN'persensitive animals, a virus of special infective activity to the blood 

 can be produced. In that case cutaneous inoculation of the blood or its components separa- 

 tely produces the characteristic pustules even in man. By using this intensified virus a wide- 

 spread eruption is easily caused in man (4 cases out of 12 inoculated), but the virulence may 

 be reduced if the blood is kept on glass for a given period, in the presence of oxygen. 



In comparative studies of cow-pox and foot-and-mouth disease, the writer found that the 

 two viruses behave sinrilarly as regards local and general immunit\'. In some cattle which 

 had been inocuUited with positi\-e results more than 7 years since, he observed that the immunity 

 persisted as regards cutaneous inoculation or quite temporary reactions jilone were produced, 

 while when inoculated on the mucous membrane (tongue) characteristic pustules were obtained 

 but then the virus did not pass into the blood. If, on the other hand, young animals are used 

 which have never been infected (preferably meadow-fed, as then less liable to contagion through 

 human vaccination), whatever the channel of entrance, the virus passes into the blood and con- 

 tinues present there during the febrile period . 



(2) See B. 1915, No. 1314. 



