in ANALYSIS OF PLAGUE MATERIALS 47 



mentioned above, is for all practical purposes perfectly 

 sufficient. Moreover, my experience leads me to suspect 

 that failure by Dr. Pakes and his colleague in identify- 

 ing the B. pestis in the earlier cases of pneumonia in 

 Johannesburg might have been due to the cultures not 

 having been made by plates, but in tubes. 



The second point I wish to point out, and to insist on, 

 is this : it ought to be remembered that in sputum of 

 acute lung affections, besides the Diplococcus pneumonice 

 there may be, and occasionally are present, coli-like 

 microbes, or microbes belonging to the proteus group ; 

 both these microbes in film specimens of the sputum, well 

 stained and well washed, appear as bipolar oval to 

 cylindrical rods not unlike B. pestis. In these cases to 

 make diagnosis " plague " or even " probably plague " 

 from the microscopic examination alone would be quite 

 unjustifiable, and might lead to extremely embarrassing 

 results. Some observers appear to place, with Hankin, a 

 certain diagnostic reliance on the capability of the plague 

 microbe to grow into long threads in salted media. I 

 have shown many years ago, i.e. long before Hankin, that 

 a number of different bacteria (including B. coli and those 

 of the coli group) when grown in media containing excess 

 of salt grow into long filaments ; it is therefore clear that 

 this modification can be of no diagnostic help. 



Moreover, these lung B. coli and lung proteus, when 

 injected into the groin of the guinea-pig in sufficient 

 amounts, cause acute septicaemia : hadmorrhagic effusions 

 extending over the thigh, groin, abdomen, and even the 

 chest wall ; the effusion is crowded with the bacilli, and 

 these in film specimens show bipolar staining and are Gram- 

 negative. Owing to this morphological and experimental 



