^®^^J VETERINARY MEDICINE. 879 



the complement with serum samples obtained from hogs which gave a positive 

 reaction to the spleen antigen extracts." 



Experimental antigens were also prepared from the intestinal button ulcers 

 of hogs affected with the chronic type of the disease. No definite conclusions 

 however, could be drawn from the positive reactions obtained with these anti- 

 gens, since the necrotic ulcers used undoubtedly contained " a number of con- 

 taminating micro-organisms and toxic products which have no causative rela- 

 tion to hog cholera but which under certain conditions possibly may stimulate 

 the production of their special antibodies in the blood of a cholera-infected hog. 

 B. coli communis, B. suipestifer, B. nccrophorus, and Spirochceta hyos have all 

 been found in these ulcers." 



Small quantities of the positive-reacting ulcer material injected into sus- 

 ceptible pigs produced typical cases of hog cholera. Preliminary data indicate 

 the possibility of ultimately using the complement-fixation test in determining 

 the variations in the potency of serum. An attempt is being made to isolate 

 the antigen from the positive-reacting spleens and ulcers in as pure a form as 

 possible. 



In contagious abortion investigations, " 29 suspected herds, comprising a total 

 of GIO cattle, have been tested. Including animals retested, 1,218 blood-serum 

 samples have been examined. Twenty-four, or a little over 80 per cent, of the 

 suspected herds contained positive-reacting animals with a history of abortion. 

 In one herd, in a group of 70 cows, 41 gave a positive reaction, and 29 a nega- 

 tive reaction. ... In other herds the percentage of positive reactors was less. 

 Taking the entire number of animals tested in the infected herds 43 per cent 

 gave a positive reaction." 



The value of the test to the cattle owner in preventing the spread of the 

 infection and in its eradication is indicated. 



Text-book of meat hygiene, R. Edelmann {LehrMich der Fleischhygiene. 

 Jena: Gustav Fischer, 1914, 3. rev. ed., pp. XVI+442, pis. 4, figs. 221). — The 

 third revised German edition of this work, of which American editions have 

 been previously noted (E. S. R., 35, p. 681). 



The physical chemistry of disinfection, I, J. F. Norton and P. H. Hsu 

 (Jour. Infect. Diseases, 18 (1916), No. 2, pp. 180-194, fig. i).— The results of 

 the study reported are summarized as follows : 



Acids act as disinfectants through the agency of the hydrogen ions produced 

 by electrolytic dissociation. The disinfecting power of an acid is approxi- 

 mately proportional to the hydrogen-ion concentration. The addition to an 

 acid of a salt containing an anion common to this acid diminishes its disinfect- 

 ing power, as the result of a decrease in the hydrogen-ion concentration and an 

 increase in the concentration of the undissociated acid molecules. Salts which 

 do not appreciably affect the dissociation of an acid greatly increase the disin- 

 fecting properties of the acid. Acid anions are positive catalyzers and undis- 

 sociated acid molecules are negative catalyzers la acid disinfection. 



The early determination of pregnancy in domestic animals, E. R. Wecke 

 (Flugschr. Deut. Gesell. ZUcMungsk., No. 35 (1915), pp. 56). — This pamphlet 

 discusses the importance to the breeder of an early diagnosis of pregnancy, 

 the methods commonly employed, the theoretical principles of the dialysis 

 procedure, and the anatomical possibilities of the entrance of fetal material 

 into the circulating blood of the mother. The dialysis method and its manipula- 

 tion are described in detail. 



From experimental data reported the author concludes that the dialysis 

 procedure is a valuable and accurate method for the determination of preg- 

 nancy in cattle, especially In the early stages where the usual means of 



