84 EEPOET OF OFFICE OF EXPERIMENT STATIONS. 



tamination through contact with the air in an open room is pre- 

 vented. The station has shown by experiments that the bacterial 

 content of the milk is very greatly increased by the usual methods 

 of artificial cooling in an open room, and its device avoids this. 



In connection with the investigations of the bacillary white diar- 

 rhea in chickens, the Connecticut Storrs station in cooperation with 

 Yale University claims to have isolated the organism which causes 

 the disease, and thus definitely determined the cause of this trouble. 

 Suggestions are made for its avoidance. 



Much success has been secured in the use of serum against hog 

 cholera, and in several States the stations are preparing the serum 

 under State ai^propriation. The Minnesota station reported no 

 failures when full doses of tested serum were given in herds not 

 already affected, and when herds already infected were treated the 

 results were as satisfactory as could be reasonably expected. Up to 

 March 1, 1910, 1,004 individuals in infected herds were vaccinated, of 

 which G9 died, while 70 out of 76 not vaccinated died. In sound 

 herds 982 were vaccinated with a full dose of tested serum, of which 

 12 died. All vaccinated hogs were tested by inoculation or exposure. 

 During the year data were also secured indicating that pigs from 

 immune sows are born with very high resistance to cholera. This 

 natural immunity is gradually lost, but is sufficient up to five weeks 

 of age to permit such pigs to be inoculated with very high virulent 

 blood with an unimportant percentage of loss. 



The Indiana station reports the discovery that normal salt solution 

 which has been injected into the abdominal cavity of a hog affected 

 with cholera can be substituted for virulent blood in the preparation 

 of hyperimmune hogs. This has cheaj)ened the treatment fulh'^ one- 

 third, and is held to be the most important discover}^ since the present 

 method of treating hog cholera was introduced. In these experi- 

 ments a normal salt solution was injected into the abdominal cavities 

 of a number of hogs used in the work. Two hours later these 

 hogs were bled and as soon as the animals had died the virulent 

 salt solution was removed. Eleven hyperimmunes were produced 

 with this normal salt solution and all of them yielded potent 

 serum. 



The deterioration of cement under the action of alkali has been 

 studied at the Montana station. The action of alkali salts destroys 

 the binding material of the cement (calcium hydrate), and also 

 increases the volume of the mass, making it bulge and crack and 

 crumble. This is a matter of great importance in the alkali regions 

 in connection with the construction of irrigation works and farm 

 buildings, as well as other structures. Means for preventing the de- 

 terioration have been proj)osed. 



