1946 Journal of Applied Microscopy 



of the filter with the liquids which are supposed to contain the typhoid bacillus, 

 and place it in the incubator at 37° for from fifteen to forty-eight hours, the 

 length of time depending upon the porosity of the filter. The bouillon surroupd- 

 ing.the filter is at first perfectly clear, but soon becomes cloudy, thus demonstrat- 

 ing the passage of the microbe through the pores of the porcelain filter. 



When this takes place remove aseptically by means of a slender sterile pipette, 

 a certain quantity of the cloudy bouillon and make the microscopic examination 

 and the tests for the agglutination reaction with the typhoid bacillus ; inocula- 

 tions should also be made upon ordinary bouillon, upon litmus lactose broth, 

 upon milk, lactose gelatin, potato, etc., in order to identify the bacillus. Instead 

 of the alkaline salted bouillon of which we have just spoken, ordinary neutral 

 bouillon may be used ; but in that case certain classes of very mobile colon ba- 

 cilli traverse the porous wall and interfere with the diagnosis. Under these con- 

 ditions it has been found that the addition to the ordinary neutral bouillon of 

 sodium hydroxid, in increasing amounts, at first furthers the development of the 

 colon bacillus and then hinders it almost immediately. Under the same con- 

 ditions the development of the bacillus of Eberth continues equally, at a maxi- 

 mum rate for a weak alkalinity; but maintains a perceptibly constant value, equal 

 to the maximum, so long as the amount of sodium hydroxid added to the solution 

 of 3 per cent. Defresne solution does not reach a concentration of more than 1 

 to 2 grams per liter. If this concentration is exceeded the difficulties which the 

 cultures of the colon bacillus and those of the typhoid present become very con- 

 siderable, and it is only by the use of extremely alkaline media that mixed cul- 

 tures of colon and typhoid bacilli may be obtained in which the latter is not 

 destroyed first. 



Unfortunately the addition of soda to the bouillon hinders the mobility of 

 the typhoid much more rapidly than it does that of the colon bacillus. Sea salt, 

 added to the bouillon, has a very valuable effect in this method — that of restoring 

 to the typhoid bacillus its original mobility, even after it has been hindered by the 

 soda, and also that of destroying the mobility of any colon bacilli which may 

 have persisted. This special alkaline and salted bouillon possesses the great 

 advantage of allowing the bacillus of Eberth to vegetate under favorable con- 

 ditions, and to retain its mobility, while hindering the development and mobility 

 of the colon bacillus ; in this case alone does the typhoid bacillus traverse the 

 porous wall first. 



To sum up: In combining, as has just been said, the action of the soda and 

 the sea salt, a bouillon can be made which, with the help of the cultures on the 

 filters, admits of the separation, beyond a possibility of doubt, of typhoid from a 

 definite colon bacillus. In practice, when the typhoid bacillus is to be separated 

 from water, or from a salt which also contains colon bacilli of unknown nature, 

 it is advisable to inoculate several tubes containing the porous filters, and 

 stocked with alkaline bouillon containing increasing quantities of salt. In order 

 not to alter the concentration of the bouillon, it is wise to introduce into the 

 filter tubes only a few drops of the suspected liquid ; or even when it is desira- 

 ble to make a test upon a considerable volume of the liquid, it is preferable to 

 filter it previously on a porous filter and to use for inoculation only the light 

 film adhering to the surface of this auxiliary filter. A. Girauld. 



Tr. by Eleanor L. Lattimore. 



