184 OMENTAL PLAGUE chap. 



in each instance thoroughly mixed with the gelatine and 

 then placed over sulphuric acid, of course in a hermetically 

 closed space. The earth as also the sand were (after being 

 kept not more than twenty-four hours over sulphuric acid) 

 found perfectly dry and hard. After having been thus 

 dried during one, two, three, or more days, a small amount 

 (about \ to 1 gramme) of the infected earth or sand was 

 in each instance taken out, placed in a sterile watch-glass 

 and distributed (rubbed down) in a few cubic centimetres 

 of warm sterile water so as to form a turbid emulsion. 

 Of these turbid emulsions small quantities in each instance 

 (about T ^, \ y \ cc.) were injected subcutaneously into 

 guinea-pigs. This method of procedure was chosen in 

 preference to mere cutaneous inoculation of rats, for the 

 reason that the object was to ascertain not whether living 

 plague bacilli were present in a small droplet (the quantity 

 that could be introduced by cutaneous inoculation) but 

 whether any living plague bacilli were left in fair 

 quantities of the materials. 



Experiment 1. — Guinea-pig No. 1 injected with 

 " sand - gelatine,'' after -twenty -four hours' drying, on 

 July 2. Guinea-pig No. 2 injected with " earth-gelatine," 

 after forty-eight hours' drying, on July 4. 



Guinea-pig No. 1 developed a big bubo and died on 

 July 7 with typical subacute plague. Post-mortem 

 examination showed a necrotic bubo with crowds of 

 B. pestis ; spleen and liver dotted all through with white 

 nodules full of B. pestis. 1 



1 It may not be unnecessary to state that in all experiments mentioned here, 

 inclusive of all animals without exception dead or killed after plague infection, 

 stained film specimens of all affected organs, and culture on gelatine from the 

 bubo (when present), from the intestine (when affected), from the spleen and from 

 the heart's blood, were made invariably and as a matter of ordinary routine. 



