APPENDIX 481 



tions (the skin having been washed with 1-1000 corrosive sublimate, and 

 shaved). In less than a fortnight's time, if the inoculated milk contained 

 a considerable number of tubercle bacilli, typical infection of the 

 popliteal and inguinal glands can be detected. If the milk contained 

 very few bacilli the infection is much slower (fifth week). After the 

 animal has been killed the presence of the tubercle bacilli can be 

 detected in the inguinal glands and the spleen. Some workers make it a 

 rule to inoculate two guinea-pigs from the sediment of the milk, one 

 receiving half of the sediment subcutaneously in the groin, the other 

 receiving the other half intra-peritoneally. 



BACTERIOLOGICAL DIAGNOSIS IN SPECIAL DISEASES 



1. Diphtheria. Obtain a piece of the membrane or a " swab " from 

 the throat. Take a piece of stout iron wire and twist a piece of cotton 

 wool round one end of it, and insert in a test-tube, and sterilise. By 

 means of such a swab obtain a rubbing of the suspected throat. Then 

 scraping off from the swab sufficient material for (a) a microscopic 

 examination, (6) smear the swab over the surface of agar and blood 

 serum media, and finally (c) place in a tube of sterilised broth. Thus 

 we have material for a film preparation, for cultivation, and for animal 

 inoculation. Make the film in the usual way, and stain with Nicolle's 

 modification of Gram (see' p. 458) or Neisser's stain (see p. 476). 

 Examine under the microscope. The value of examining such a prepara- 

 tion microscopically depends upon the experience of the bacteriologist. 



Of culture media, blood serum is perhaps the best, but, if no serum 

 tubes can be had, an egg may be used. It should be boiled hard, the 

 shell chipped away from one end with a knife sterilised by heating, and 

 the inoculation made on the exposed white surface ; the egg is then 

 placed, inoculated end downwards, in a wine-glass of such a size that it 

 rests on the rim and does not touch the bottom. A few drops of water 

 may with advantage be put at the bottom of the glass to keep the egg 

 moist. The preparation is kept in a warm place for twenty-four to 

 forty-eight hours, and then examined. The examination, of course, 

 consists in staining and preparing specimens for the microscope, and 

 observing the form, arrangement, and characters of the organism or 

 organisms present. The same is done for cultures on agar or blood serum. 

 On the latter the colonies show characteristic growth. A small piece of 

 the membrane may be detached, washed in water, and stained for 

 the bacilli. 



To differentiate the true or Klebs-Loffler bacillus from the pseudo 

 or Hofmann bacillus, note especially that Hofmann's bacillus is plumper, 

 shorter, and thicker in the middle than the true diphtheria bacillus. It 

 also stains more regularly, grows better on alkaline potato, and produces 

 an alkaline reaction in neutral litmus agar or bouillon incubated for two 

 days at 37 C. It is non-pathogenic for guinea-pigs, whereas the Klebs- 

 Loffler bacillus is pathogenic. 



2. Tetanus. The detection of the bacillus of tetanus in the dis- 



2 H 



