FOOT-AND-AIOUTH DISEASE 87 



even boiling for a short time without especial precau- 

 tionary measures, is not always sure to kill all bacilli, 

 because there is a jjart of the milk (little drops on the 

 ui^per part on the vessel, bubbles, scum or froth on the 

 surface) which is not thoroughly heated. It is, there- 

 fore, a matter of great importance to determine whether 

 the forms of aj^ijaratus used for pasteurization are 

 really so constructed that all of the milk is equally heated 

 to a desired temperature. At present, nothing definite 

 can be said about this, since no investigations have been 

 made to determine the amount of froth formation and 

 the temperature the froth reaches in the different forms 

 of api^aratus. When market milk is pasteurized the 

 functional cajiacity of the apparatus should be very 

 cai'cfully tested. 



b. Foot-and-mouth disease. It lias long been known 

 that milk from cows with foot-and-mouth disease is infec- 

 tious, and may carry the disease to man. A hundred 

 yt'ais ago, in South Germany, the use of milk from sut'li 

 cows was in'ohibited for use as food for num. In the 

 lighter forms of the disease the milk remains unchanged, 

 but with cows badly affected, there is not only a decided 

 diminution in (piantity, but its appearance and comi)osi- 

 tion ai'c changed. In such cases, the milk becomes thin, 

 separates a slimy layer of cream, of dirty color, and there 

 is quite abundant sediment or, as happens infrequently, 

 it becomes richer in fat with a simultaneous falling off 

 in quantity. Under the microscope, leucocytes and 

 broken-down tissue-cells are found in greater quan- 

 tity than usual, sometimes red corpuscles also. The 

 milk contains a greater ([uantity of albumin and globulin 

 than usual, so that when boiled, large clumps and flakes 

 sei>arate and the sugar and casein fall off in quantity — 

 all changes which are symptomatic of an admixture of 

 inflammatorv exudate. 



