676 EXPERIMENT STATION RECORD. 



" Species of Oidium, Alternaria, aud Cladosporium can not develop in butter 

 coulaiuiug 2.5 per cent of salt. The occurrence of any of tbese forms In a 

 sample of butter indicates low salting. Excess of curd favors mold growtb. 

 Well-washed butter is less subject to mold. Leaky butter, i. e., butter from 

 which water of buttermilk exudes and collects in the wi'appings or in the con- 

 tainer, furnishes the best conditions for the beginning of mold growth. From 

 these wet areas colonies may spread to the butter itself. 



" Wet surfaces, wet wrappings, or high humidity, are es.sential to mold growth in 

 butter. Mold will not grow upon the surface of a piece of butter exi^osed to 

 humidities of 70 per cent or lower. The water in the butter is thus not suffi- 

 ciently available to the mold to support the development of a colony, unless 

 evaporation is reduced liy high humidities. In clo.sed packages, wet or damp 

 cellars, or carelessly packed masses with cracks or fissures in which moisture 

 collects, mold may seriously injure the appearance of butter packages or 

 actually induce great changes in the butter itself. Salt up to 2.5 to 3 per cent 

 in butter is sufficient to eliminate mold or reduce it to negligible amount. This 

 is equivalent to the use of a 12 to 15 per cent brine," 



A bibliography of ten references is given. 



VETERINARY MEDICINE. 



A system of veterinary medicine, edited by E. W. Hoaee (Chicago: Alexan- 

 der Eger, 1915, vol. 2, pp. XVIII-\-162S). — This second volume of the work 

 previously noted (E. S. R., 29, p. 476) deals with general diseases and includes 

 a section on parasites and parasitic diseases. An index to the two volumes is 

 given. 



Report of the veterinary department, R. A. Ceaig (Indiana Sta. Rpt. 1914, 

 pp. 72-76). — During the year 38 per cent more of antlhog-cholera .serum was 

 prepai'ed than in any previous year. In the field work all healthy hogs wei'e 

 vaccinated by the serum-simultaneous method and the cholera hogs were given 

 the serum alone. Many deaths resulted amongst the vaccinated healthy hogs 

 due to infection of the vaccination wound at the time of vaccination or shortly 

 afterward. 



A few of the simultaneously vaccinated herds lost their imnnniity in from 

 six weeks to six months post vaccination. In nearly every case the pigs that 

 lost the immunity received only 0.5 cc. of hog cholera blood. " Field ex- 

 perience indicates that it is not advisable to administer less than one cc. of 

 virus, or simultaneously vaccinate pigs that weigh less thap 50 lbs., especially 

 if the mother is actively immune." 



In the hog cholera investigations hog cholera blood and virulent normal salt 

 solution were studied with the ultramicroscope and various culture media such 

 as milk, hay, and meat infusions, bouillon, and sugars were used in combina- 

 tion with filtrates of virulent blood. More than 60 germ-free filtrates were 

 studied. 



For the purpose of determining variations in the virulence of hog cholera 

 blood at different periods in the disease, virus was secured by tail bleeding a 

 cholera hog four and six days after it had been inoculated. Twelve pigs given 

 the four-day virus lived an average of 24 days while those given the six-day 

 virus lived only 21 days. 



A mixture consisting of one part hog cholera blood and two parts normal 

 salt solution was incubated at a temperature of 37.5° C. for 24 hours. The 

 different lots of virus were then heated from one to two hours in a water 

 bath at temperatures ranging from"" 60 to 65°. Of 62 pigs inoculated with 



