ROUTINE EXAMINATION OF MATERIAL 139 



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 uncontaminated 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 obtained easily only by inoculation experiments. 



Routine 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. 61) should be made 

 and incubated at 37 C. Method b of course gives results 

 more quickly. In every case when an unknown disease is 

 being investigated, some of the material should be subjected to 

 methods suitable to the growth of anaerobic bacteria. If micro- 

 scopic investigation reveals the presence of bacteria, it is well 

 to keep the material in a cool place till next clay, 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 two hundred 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 1 The shape of the colony, its size, the appear- 

 ance of the margin, the graining of the substance, its colour, 

 etc., are all to be noted. One precaution is necessary, namely, 

 it must be noted whether the colony is on the surface of the 



