526 Messrs. W. E. Bullock and W. Cramer. On a Neiv 



salt and the bacteria are injected into the same site. It does not appear 

 reasonable to suppose that this local effect is due to the actual presence of 

 calcium salts at the site of injection. Since the effect is produced only by 

 soluble, ionisable calcium salts, it would be necessary to assume that such a 

 salt could remain deposited at the site of injection for a day or even three 

 days. Moreover, if that w^ere so, it ought to be possible to counteract their 

 effect by injecting sodium citrate together vs^ith the bacterial suspension. 

 That, however, we have been unable to do. In one experiment, for instance, 

 eight mice received an injection of 2'5 mgrm. of calcium chloride in the 

 right flank. Two hours afterwards four of the mice received a suspension of 

 Vibrion septique spores in saline in the right flank, while the other four 

 received a suspension of these spores in 2 per cent, sodium citrate solution, 

 also in the right flank. All the eight mice were dead within 24 hours with 

 the typical^ local lesion of gas gangrene. Similar experiments have been 

 carried out with the same result. Sodium citrate only protects when it is 

 mixed with the calcium salt before it is injected into the animal. 



One must conclude, therefore, that calcium salts produce a local change 

 in the tissues at the site of injection. This conclusion is confirmed by the 

 fact that it is much more difficult to produce gas gangrene and tetanus when 

 the bacteria and the calcium salts are injected at different sites, than when 

 they are injected at different times. The local change produced in the tissues 

 by calcium salts persists for a considerable time, and has, as the ultimate 

 result, the formation in the animal of a place of diminished resistance against 

 the infecting bacteria. The most striking confirmation of this conception 

 is furnished by the result of the experiments in which gas gangrene occurred 

 after injection of the calcium salt and bacterial suspension at different 

 sites. For in these experiments the fact was observed that the typical local 

 lesion of gas gangrene — an intense haemorrhagic oedema — occurs always at 

 the site of injection of the calcium salt, while the site where the bacteria 

 have been injected does not show, as a rule, any macroscopic evidence of gas 

 gangrene. Films made from the two sites present this difference very 

 strikingly (see fig. 1); the film from the site of injection of B. Welcliii shows 

 active lysis, as indicated by the presence of bacterial ddhris, and active 

 phagocytosis with intracellular digestion of the engulfed bacteria. Only a 

 few bacteria can still be seen lying free and apparently intact, but many of 

 these have become gram-negative. The picture is practically identical with 

 that given by a normal mouse which has received a suspension of detoxicated 

 bacteria, and which is defending itself successfully against the infection. 

 But the film from the site of injection of the calcium salt presents the picture 

 typical of an animal which has developed gas gangrene by, let us say, the 



