in ANALYSIS OF PLAGUE MATERIALS 45 



possibly overlooking a case of plague at a time when 

 occurrence of plague in their respective districts — after 

 the numerous cases of plague that had landed in ports of 

 these Islands — could not be excluded. 



Several points which ought to be here mentioned in 

 connection with the culture test I consider of particular 

 importance. The first point is this : surface plates on 

 agar ought in all instances to be made with the materials 

 submitted. A fair amount of the material, several drops 

 of the juice of bubo or inflamed gland, of the lung, of the 

 spleen when available, are rubbed over the surface of 

 nutrient agar (beef broth, peptone, salt, agar), solidified in 

 a plate dish of good size (three inches diameter). If 

 B. pestis are contained in the submitted material they are 

 sure to be discovered in twenty-four to thirty-six hours at 

 37° C. incubation. I have never failed to find them even in 

 cases in which film specimens failed to give clear indica- 

 tion of their presence. If film specimens already show 

 B. pestis or bacilli like them in great numbers, agar tubes 

 (slanting surface) will bring them forth, but such cases 

 are not often submitted; the materials generally sub- 

 mitted are in the great majority of instances such as 

 contain few B. pestis amongst other microbes, or contain 

 few B. pestis only. In the former instance, if the inocula- 

 tion has been made in a tube, the few colonies of B. pestis 

 become generally overgrown or crowded out by other 

 microbes (cocci, bacilli) ; in the latter, not enough material 

 is used for development on the limited surface of the agar 

 tube. 



The great importance of using at once plate cultures in 

 preference to tube cultures of solid or fluid media cannot 

 be sufficiently emphasised. If B. pestis is mixed in any 



