112 ABSTRACTS 



Health has used three dilutions of potassium tellurate: e.g., 1.4, 1.5, 

 and 1.6 cc. of a 1 per cent solution of freshly made up potassium tel- 

 lurate for each 100 cc. ordinary Loeffler blood serum. 



Three hundred and eleven parallel diagnostic cultures on ordinary 

 Loeffler's blood serum and the same number containing 1.6 cc. potassium 

 tellurate per 100 cc. were made. This dilution of potassium tellurate 

 medium gave 2 per cent less positives than the Loeffler's blood serum. 

 Of 246 parallel diagnostic cultures on ordinary Loeffler's blood serum 

 and the same number containing 1.4 cc. potassium tellurate per 100 

 cc, the dilution of potassium tellurate medium gave 1.2 per cent less 

 positives than did the Loeffler's blood serum. Of 890 parallel diagnostic 

 cultures on ordinary Loeffler's blood serum and the same number con- 

 taining 1.5 cc. potassium tellurate per 100 cc. the potassium tellurate 

 dilution medium gave 2 per cent more positives than the Loeffler's blood 

 serum. 



The increased number of positives obtained with the potassium 

 tellurate medium is not by any means a measure of the complete 

 advantage of this medium. Smears made from the potassium tellurate 

 medium contain fewer bacteria, and their use decreases the time neces- 

 sary to examine the microscopic slides almost half and lessens the work 

 of getting pure cultures enormously. 



The Number of Bacteria in the Air of Cow Stables. G. L. A. Ruehle. 



In the course of an investigation of the air as a source of bacteria in 

 milk which has been made at the New York Agricultural Experiment 

 Station, it was necessary to make a large number of analyses of stable 

 air under a variety of conditions. Altogether 1130 separate analyses 

 of air samples were made but since many of them were duplicate 

 analyses or were made under artificial conditions only 402 analyses are 

 summarized in the work reported upon here. Of these 344 were made 

 in the Station stable and 58 in commercial dairy stables. The aero- 

 scope used in the majority of cases was a simple modification of the 

 sand filter aeroscope recommended by the Committee on Standard 

 Methods for the Examination of Air. The modification was of such 

 a nature as to permit dry sterilization, at the same time eliminating 

 some of the joints where leakage might occur. 



The average germ content of the air in 344 tests was 115 per liter. 

 The lowest number of bacteria was found, as would naturally be ex- 

 pected, when the barn was empty and everything was quiet. Sixt}' 

 analyses made under these conditions showed an average of 41 per 

 liter. The highest average numbers were found after milking was 

 finished and silage was being fed. This caused the cattle to move 

 about, stirring up an evident dust. Ten analyses taken under these 

 conditions showed an average of 271 per liter. Individual tests among 

 the 344 analyses gave results varying from to 825 per liter. The 

 germ content of the air of thi-ee commercial stables was found to be 

 similar to that of the Station stable except that four analyses taken 



