CHAPTER III 



ANAEROBIC ORGANISMS : THEIR ISOLATION AND CULTURE 



General Note. Cultivation in Hydrogen and in vacuo. Hydrogen Production. 

 Methods of Isolation and Culture. 



General note— 



The fermentative and other changes produced in milk by 

 organisms of the anaerobic type are of so important a nature 

 that a thorough knowledge of the technique employed in this 

 special branch of research is essential to those who would study 

 the bacteriology of milk, and it is proposed in this chapter to 

 explain in some detail the principal methods employed in the 

 various English, German, and French schools, as well as those 

 which the writers have themselves found most useful in research 

 work. 



For the study of the phenomena attending anaerobic fermenta- 

 tion the special flasks illustrated on Plate 9 will be found con- 

 venient, and are easily set up. Flask " A " is specially useful for 

 the study of the progressive phenomena of anaerobic fermentation, 

 as it permits, up to a certain stage, of the examination of the milk 

 at intervals without admission of outward air, or the disturbance 

 of the existing anaerobic conditions, the pressure set up in the 

 interior of the flask by the disengagement of gas being sufficient 

 to cause the liquid under examination to fall drop by drop into 

 a receptacle placed underneath the curved outlet tube. The 

 apparatus consists of a three-necked Wolff flask of 400 to 500 c.c. 

 capacity, arranged as in figure. The flask is closed with india- 

 rubber one-holed corks, through the two side ones of which are 

 led lengths of glass tubing reaching in each case to the bottom 

 of the flask, the one being bent at the top at a right angle with 

 a return of about i inch, constricted at the point of entry into 

 the cork, lightly plugged with cotton-wool, and terminating with a 

 short length of vacuum tubing fitted with a screw pinchcock as 



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