INFECTIONS OF THE DIGESTIVE TRACT 113 



part by weight to ten parts of normal salt solution answer 

 very well as a material for making the smears. The 

 following technique serves satisfactorily for routine work. 

 One stains for three minutes with the Gram solution 

 of gentian violet. The solution is then allowed to run 

 off the slide, but the latter is not washed. Lugol's solu- 

 tion of iodine is then permitted to act for two minutes. 

 The slide is now rinsed with water and decolorization 

 is practiced for one-half minute by means of absolute 

 alcohol. The smear is then restained with a fuchsin 

 solution. Unless one employs approximately the same 

 technique, varying and confusing results are obtained 

 which make it almost impossible to say with confidence 

 which organisms are Gram-negative and which are Gram- 

 positive. 



From the use of the Gram method one obtains some 

 idea as to the numbers of microorganisms resembling 

 the colon bacilli in morphology; one may form a judg- 

 ment as to the state of their preservation, as to the pres- 

 ence or absence of slender, long, Gram-negative organ- 

 isms of the type of B. liquefaciens ilei; a judgment may 

 be formed as to the numbers of Gram-positive diplococci 

 and other coccal forms ; an opinion may be formed as to 

 the probability of the presence of B. bifidus, especially 

 in its unbranched form; and finally it is possible, after 

 one has had experience, to make an estimate as to whether 

 free spores and spore-holding organisms and vegetative 

 anaerobic forms are present in excessive numbers. None 

 of these microscopical appearances can be regarded as 

 positive evidence of the identity of the dominant bacteria 



