ISOLATION OF ANAEROBES 



447 



It is, of course, desirable to make use of methods that may be 

 appHed to the largest possible number of species, that are easy of 

 manipulation, and moderate as to cost of time and material. 



The organisms present in material to be investigated may belong 

 in any one of four large groups, which may be described as follows: 



Whatever be the material that is to be investigated, a micro- 

 scopic examination of a Gram stain is first in order. Practice 

 only will enable the worker to form judgments which will be of 

 value to him. As hints to the beginner, one may suggest that 

 there are an endless number of species of anaerobes and that 

 specific diagnosis by microscopic examination is futile. There 

 are frequently many species of anaerobes in the material that 

 finds its way to a laboratory, and, unless a study of many strains 

 is intended, the isolation or demonstration of a single species, 

 whose nature is guessed at, must be attempted. If the micro- 

 scope shows the probability of the presence of that species, matters 

 are simplified. To seek a certain organism one should familiar- 

 ize himself with a pure strain of that type of organism, or study 

 photographs or drawings of it; verbal descriptions are not of 

 much value. He should also learn the colony form of several 

 strains of the type he desires to obtain. The employment of a 

 medium in which the morphology of the organisms is varied and 

 characteristic is imperative. This laboratory uses chopped meat 

 medium containing 5 per cent peptic digest broth (pH 7.2) for 

 routine cultivation and this medium excels all other autoclaved 

 media in the above respect. The use of oil over the medium to 



JOURNAL OF BACTERIOLOQT, VOL. VI, NO. 5 



