ROUTINE EXAMINATION OF MATERIAL 117 



suitable distances, according to the amount of fluid to be taken. 

 The fluid is drawn up into the part between the constrictions, 

 but so as not to fill it completely. The tube is then broken 

 through at both constrictions and the thin ends are sealed by 

 heating in a flame. 



Solid organs to be examined should, if possible, be obtained 

 whole. They may be treated in one of two ways. 1. The 

 surface over one part about an inch broad is seared with a 

 cautery heated to dull red heat. All superficial organisms are 

 thus killed. An incision is made in this seared zone with a 

 sterile scalpel, and small quantities of the juice are removed by 

 a platinum spud to make cover-glass preparations and plate or 

 smear cultures. 2. An alternative method is as follows : The 

 surface is sterilised by soaking it well with 1 to 1000 corrosive 

 sublimate for half an hour. It is then dried, and the capsule of 

 the organ is cut through with a sterile knife, the incision being 

 further deepened by tearing. In this way a perfectly uncon- 

 taminated surface is obtained. Hints are often obtained from 

 the clinical history of the case as to what the procedure ought 

 to be in examination. Thus, as a matter of practice, cultures 

 of tubercle and often of glanders bacilli can be easily obtained 

 only by inoculation experiments. Typhoid bacilli need hardly 

 be looked for in the faeces after the first ten days of the disease, 

 and so on. 



Eoutine Procedure in Bacteriological Examination of 

 Material. In the case of a discharge regarding which nothing is 

 known the following procedure should be adopted : (1) Several 

 cover-glass preparations should be made. One ought to be 

 stained with saturated watery methylene-blue, one with a stain 

 containing a mordant such as Ziehl-Neelsen carbol-fuchsin, one 

 by Gram's method. (2) (a) Gelatin plates should be made and 

 kept at room temperature, (b) a series of agar plates or successive 

 strokes on agar tubes (p. 55) should be made and incubated at 

 37 C. Method (b) of course gives results more quickly. If 

 microscopic investigation reveals the presence of bacteria, it is 

 well to keep the material in a cool place till next day when, if 

 no growth has appeared in the incubated agar, some other culture 

 medium (e.g. blood serum or agar smeared with blood) may be 

 employed. If growth has "taken place, say in the agar plates, 

 one with about 200 or fewer colonies should be made the chief 

 basis for research. In such a plate the first question to be 

 cleared up is : Do all the colonies present consist of the same 

 bacterium '? The shape of the colony, its size, the appearance of 

 the margin, the graining of the substance, its colour, etc., are all 



