92 MICHIGAN ACADEMY OF SCIENCE. 



are killed by the use of one pait of formaldelnde to five thousand of 

 milk within one da}'. 5. In the strength of 1:8000 the lactic acid 

 bacillus is much retarded in its growth until the end of the second day, 

 when it begins to grow abundantly. The typhoid bacillus is retarded 

 until the end of the first day, but grows more abundantly during the 

 second and third, and died out altogether before the sixth day. The 

 colon bacillus is retarded in its growth until the end of the first day, 

 after Avhich it grows abundantly. 0. In the strength of 1:10000 the 

 lactic acid bacillus does not grow abundantly until after the second 

 day, while the typhoid bacillus is nearly exterminated at that time; 

 but the colon bairillus grows luxuriantly after that time. In a strength 

 of 1:25000 there is a decrease in the number of colonies of the lactic 

 acid bacillus during the first day, after which there is a gradual in- 

 crease. The typhoid bacillus growth decreases in numbers, while the 

 colon bacillus growth increases from the beginning; in, other Avords, 

 formaldehyde in milk in the proportion of 1:25000 does not retard the 

 growth of the colon bacillus. S. In the strength of 1:50000 the growth 

 of the lactic acid bacillus is retarded during the first day; that of the 

 typhoid bacillus is not markedly affected until after the second day; 

 while the growth of the colon bacillus is not influenced. 



