676 EXPERIMENT STATION BECOBD. [Vol.35 



are different, for the body tissues and fluids are protected by the mucous mem- 

 branes against the ravages of the bacteria that enter with the food. Therefore 

 it can not be assumed that bacteria which are pathogenic to inoculated laboratory 

 animals would be injurious to human beings when present in the milk consumed. 

 It is a subject worthy of investigation. But since the bacteria of the udder 

 are parasitic in their nature, and since pathogenic varieties are sometimes 

 eliminated in considerable numbers from healthy udders, the data here re- 

 ported add evidence to the growing conviction that all milk is safer for 

 consumption after it has been pasteurized." 



Studies on the formation of gas in milk, B. W. Hammeb {Iowa Sta. Re- 

 search Bui. 21/ {1916), pp. 3-16, figs. S). — Gas forming organisms were isolated 

 from several cases of gassy curds and their action on milk both alone and in 

 combination with Bacterium lactis acidi was studied. 



" The curds secured with the gas formers alone did not resemble the original 

 curd, since but a small amount of gas was held in the curd, while double inocu- 

 lations gave extremely gassy curds. It is probable that the gassy curds occur 

 with the double inoculations, because a firm curd which will retain the gas 

 results from the acid produced by B. lactis acidi while the gas formation is 

 still in progress. On continued transferring the gas formers lost their ability 

 to produce extremely gassy curds when grown in combination with B. lactis 

 acidi, and this was accompanied by a decreased acid production in inoculated 

 milk held at 37° C. for one week. It seems likely that the decreased acid toler- 

 ance is responsible for the failure to produce extremely gassy curds. Other 

 cultures of gas formers grown in combination with B. lactis acidi failed to 

 produce extremely gassy curds, probably because of their failure to grow in 

 the presence of acid. Cultures of B. lactis acidi from different sources seemed 

 to be equally effective in the production of gassy curds when grown with the 

 gas formers isolated. 



" B. lactis acidi influenced the total amount of gas produced by the gas 

 former, sometimes increasing it and sometimes decreasing it at 37°, and always 

 decreasing it at room temperature. B. lactis acidi influenced the type of curd 

 formed very materially because of the part it played in causing a retention of 

 the gas. 



" The gas-forming organisms from the four cases described were not all the 

 same. B. communior and B. cerogenes were the two types encountered." 



Comparison of the bacterial count of milk with the sediment or dirt test, 

 H. C. Campbell {V. S. Dept. Agr. Bui. S61 {1916), pp. 6, pi. i).— The author 

 gives results of an experiment to determine whether the sediment or dirt test 

 can be wholly relied upon as a means of detecting insanitary milk at milk re- 

 ceiving stations. In the experiment the Gerber, the Wizzard, and the Lorenz 

 (E. S. R., 23, p. 180) apparatus were used. Pint samples of milk were collected 

 on the railroad station platform from the milk cans as they arrived from vari- 

 ous farmers. After preparing plates, sediment tests were made and the disks 

 were compared with the bacterial counts. 



Comparing the bacterial count vpith the Grcrber sediment test with unfiltered 

 market milk, it was found that " some samples had a high bacterial count, yet 

 tested • good ' or ' fair ' with the sediment test, while others which had a low 

 bacterial count tested ' medium ' or ' bad.' " With the Wizzard sediment test, 

 one sample classed as " good " by the sediment test contained 4,102,000 bacteria 

 per cubic centimeter, while another classed as " bad " contained only 243,000 

 bacteria per cubic centimeter. With the Lorenz sediment test one sample with 

 a bacterial count of 768,000 tested " fair " by the sediment test, and one with a 

 count of 7,200 bacteria per cubic centimeter tested " bad." 



