EXPERIMENT STATION BULLETINS. 263 



less, had an influence in restraining the effect of the oxygen in the air by keeping the 

 air away from the surface of the milk and also reducing the oxygen content which the 

 milk as it passed in a stream from the teat of the cow to the receptacle necessarily 

 acquired. An objection, however, should be offered to the use of oil for the exclusion 

 of oxygen, because it is a well known fact that oil contains oxygen in the form of 

 super-oxygenated compounds, and also probably as free oxygen. In securing the gases 

 from the milk a mercury pump was used as seems to have been the general practice 

 with Stechnow and those who followed him, to which little criticism can be offered as 

 viewed from the results obtained. 

 His analyses are as follows: — 



First Analysis. 



Carbon dioxide 77.50 per cent. 



Oxygen and nitrogen 22.50 



He obtained 7.29 c. cm. of gases from 100 c. cm. of milk and employed for his analysis 

 67.5 c. cm. of milk. 



Second Analysis. 



Carbon dioxide 81.06 per cent. 



Oxygen 1-93 



Nitrogen 17.01 



« « 

 « it 



He obtained 8.29 c. cm. of gases per 100 c. cm. of milk. He used 297.5 c. cm. of milk. 



Third Analysis. 



Carbon dioxide 75.11 per cent. 



Oxygen 4.79 " " 



Nitrogen 20.10 " " 



Total gas is equal to 6.67 c. cm. per 100 c. cm. of milk. Amount of milk used 

 256.3 c. cm. 



Pfluger (11), believing that Stechnow was open to error in his method of securing 

 the milk from the udder by shielding it as he did from the air by means of oil, attempted 

 to overcome it by another device for conducting the milk from the udder to the recepta- 

 cle without exposure to the air at all. To do this he employed a piece of rubber, fitting 

 over the teat and udder of the cow as a glove would fit upon the finger; and, by 

 means of a narrow rubber tube and glass tube was able to lead the milk into a vessel 

 of mercury and collect it over mercury. He first expelled the air from the tube by 

 milking for a time, filling the tube with milk, and then placing the free end of the 

 tube under the mercury in the container. This course may be open to criticism in that 

 there would be some leakage about the surface of the teat over which the rubber was 

 fitted, but the analyses of Pfluger indicate that he was not troubled very much by 

 the possible exposure to the air from this source and that the milk secured by this 

 method was practically free, if not wholly free, from air. Further than this, his 

 results are as satisfactory as any of the results obtained when other methods are 

 employed for securing the milk, and which, in our case, we believe, did not allow of 

 any exposure to the air at all. This will be shown later. 



Pfluger's analyses are as follows: — 



First Analysis. 



Carbon dioxide 90.45 per cent. 



Oxygen 1.19 " " 



Nitrogen 8.36 " " 



Amount of milk used was 00.77 c. cm. Amount of gas obtained per 100 c. cm. was 

 8.47 c. cm. No trace of gas was obtained after one hour. 



(11.) Pfluger's Arch. f. Physiol.. Bd. II, S. 166-173, 1869. 



