996 SOCIÉTÉ DE BIOLOGIE 



The mucosities of the throat are removed with a stérile cottonswabat 

 the end of a rod. A culture of the sérum is made by rubbing the swab 

 on ils surface. The culture is sometimes too abundant and as the 

 colonies are not isolated they cannot be neatly characterized. There- 

 fore, it is difficult to distinguish the diphtheria bacilli from bacilli 

 growing on sérum in twenty-four to forty-eight hours which are 

 generally called pseudo-diphlheria. 



Messrs. Costa, Troisier, Dauvergne bave advised a combined 

 technique. They make in the throat a swabbing which is taken to 

 the laboratory where bacilli are collected from the swab with a 

 triangular platinum wire which is used to make a culture in a Pelri 

 plate containing coagulated glucosed sérum dyed with litmus. By 

 this means they hâve obtained well isolated colonies and they may 

 keep tract of theirnumber as well as of the biochemical properlies of the 

 bacilli. 



EXAMINATION OF THE COLONIES. 



The cultnred tubes are placed in a stove at a température of 

 in degrees ; Ihe colonies of diphtheria bacilli may be seen. after 18 hours ; 

 after 24 or 36 hours they are well developed. 



There is great interest in making this examination with the naked 

 eye and a magnifying glass. 



The diphlheric colony is of a greyish white color, dry on its surface 

 with very regularly rounded and.neat edges. 



The non-diphllieric colonies are whiter, creamy and therefore rather 

 soft. They are oval, extending sliglilly lengthwise in the axis of the 

 tube when they are well developed. 



Examination of tuk mickobes. 



The diphlheric bacilli are from four to six ix long, tongled up and 

 larger at the extremities which are rounded, which makes them look 

 slightly narrow in the center, but they are never larger in the middle. 

 The long and médium size forms hâve a rather characleristic aspect 

 and are never mistaken for other microbes. The short forms are 

 sometimes difficult to differenciate with other microbes growing 

 in 24 or 36 hours on sérum. 



The body of the non-dipblheric bacilli is thickerthan the extremities, 

 one of which is often pointed; it has the shape of a shuttle or of a 

 barley seed. Il is sometimes difficult to dift'erenciate theée microbes 

 with the short diphtheric bacillus. 



