ILLINOIS STATE DAIRYMEN's ASSOCIATION. 85 



of these organisms a glass of excellent definition was required, and a 

 power of at least eight hundred diameters. Yeast cells (of bread) 

 are mountains compared with them. If anj"^ living things find their 

 way through the animal tissues and escape, as with the milk, we may 

 safely conclude it is something of this description. There is no 

 evidence that higher and larger fungi as ordinary molds are ever 

 developed from the minute forms described. 



When fresh milk from healthy cows is placed under a high 

 magnifier (500 to 1,000 diameters) the thin stratum appears violently 

 agitated by currents caused by evaporation, etc., and by the molecu- 

 lar, oscillating motion known as the Brownian movement, but no 

 bacteria can be found. Examine the same milk after it has stood in 

 a warm place a few hours, and before evidence of acidity except to 

 litinus paper is presented, a few bacteria may be observed ; before 

 coagulation they are quite common and finalh' become in some cases 

 excessively numerous. Milk put in well-stoppered, scalded vials 

 kept in a temperature of from 80° to 90° Fahr. sometimes becomes 

 very sour but suflfers no further change. But frequently after souring 

 the inclosed liquid becomes putrid and highly odoriferous. Upon 

 examining two such as these the diflTerence can be ascertained. The 

 former contains one kind of bacteria, the latter two. The first is at 

 the outset minute and spherical or cylindrical and composed of 

 joints which are often more or less bent upon each other. Its move- 

 ments are of an oscillatory character, with slight or no progress in 

 any direction. The second is not unlike the first in shape, though 

 not so distinctly composed of easily-separated joints, but it moves 

 with an endwise sliding motion of apparently, under the microscope, 

 great rapidity. One is the lactic ferment, the other is the putri- 

 factive ferment. They may occur together or either may exist with-^ 

 out the other. But the lactic organism appears either more common 

 or more active in its work. 



In one experiment three vessels were placed in the same tin 

 vessel which closed tightly. Milk fresh from a cow was placed in all 

 of the inclosed vessels, which were of glass with open top. In 

 number one the blade of a pen-knife was dipped which had previ- 

 ously been inserted in sour milk swarming with the lactic ferment. 

 In number two a minute amount of milk just coagulated was placed, 

 and number three was left as it was. Coagulation took place in 

 the order named with about two hours intervening between the first 

 and second and six hours between the second and third. After two 



