718 EXPERIMENT STATION RECORD, 



a simple one, and very small alterations in the udder can be readily detected 

 by this test. More experiments will have to be performed in order to determine 

 the exact cause of these variations. In the 2 samples where streptococci were 

 found on the plates, the catalase reading was high and the alcohol reaction 

 was positive. It seems from our experiments that a case of mammitis could 

 be determined at the dairy with these 2 tests without a bacterial count. 



" The reduction test agreed in most instances with the bacterial count ; that 

 is, whenever the sample was reduced in a short time, the bacterial count was 

 high. 



" The fermentation test corresponded in the majority of instances to the kind 

 of bacteria found on the plates. If a large number of B. suMilis or B. tnesen- 

 tericus were found present on the plates, the curd was usually peptonized or 

 digested to a certain degree. 



The acidity and temperature gave some indication of the dilutions that were 

 necessary for a bacterial count. In the samples examined the acidity was 

 fairly high, this probably being due to the age of the milk when received at the 

 laboratory. The age of the milk, so far as could be ascertained, was about 24 

 hours. The temperature of the milk, as seen by the tables, ranged between 

 14 and 25°. . . 



"The biochemic tests used are simple in their technique. The results ob- 

 tained are practically as good as those shown by plating, so far as estimating 

 the number of bacteria is concerned. Many different affections of the animal, 

 also various pathological conditions of the udder, can be detected by these 

 tests, and they would materially aid a clinical examination. Pathological 

 excretions from the udder can be demonstrated by the biochemic tests, whereas 

 a chemical and bacteriological examination often gives negative results. Fur- 

 ther investigations will undoubtedly be necessary to form definite conclusions, 

 but from this brief experiment it is hoped that others may be inspired to 

 engage themselves in similar work. These tests, if applied at the dairy or site 

 of milk production, would greatly aid the health ofiicials in controlling a milk 



supply." 



A bibliography is appended. 



Casein media adapted to the bacterial examination of milk, S. H. Atees 

 (f/. S. Dept. Agr., Bur. Ani/tn. Indus. Rpt. 1911, pp. 225-235). — This has been 

 noted from another source (B. S. R., 26. p. 576). 



A proposed modification of the ofiicial method of determining' humus, 

 O. C. SMriH (Jour. Indus, and Engin. Chem., 5 {1913), No. 1, pp. 35-37).— It 

 was found in the analyses of over 200 soils that if the 4 per cent ammonium 

 hydroxid solution of the soil as obtained by the official method is shaken after 

 di'^esting for 24 hours, and all soil possible is poured into the filter, a perfectly 

 clear solution is easily and invariably obtained. If the filtering is started in 

 the morning, it may be finished by night. 



A comparison was made of this method with the Mooers and Hampton 

 method, and the Rather method (E. S. R., 25, p. 614). Ammonium carbonate 

 gave no such changes in the color of the solution prepared by the Smith method 

 as with the solution in the Rather method. In every case the percentage of 

 ash was larger in the Smith than in the Rather method, but that of humus was 

 nearly the same. It is concluded that if in the Rather method the exact amount 

 of ammonium carbonate solution is not added each time and the other pro- 

 cedures are not alike there will be a difference in the final results. 



A simple method for preparing neutral ammonium citrate solution, A. J. 

 Patten and W. C. Marti (Science, n. ser., 37 (1913), No. 957, p. 687).— The 

 method is based on the reaction taking place between formaldehyde and am- 

 monium salts which results in the liberation of the acid and the formation of 



