140 Chainer VI 



develop fairly luxuriantly at the low temperature of 12° C. Under 

 these conditions all the inoculated frogs, even those which had 

 resisted the inoculation with ordinary bacteria (grown at 37*5° C), 

 died within a period of 48 to 56 hours, containing many bacilli in 

 the blood and organs. Dieudonn^ has not studied the essential 

 mechanism that accompanies this loss of immunity; but it is very 

 probable that, for one thing, we have here to do with a reinforcement, 

 special for the frog, of the bacillus that has become accustomed 

 to develop at a low temperature. This bacillus must multiply, in 

 frogs that have been maintained at a low temperature, much more 

 rapidly and profusely than would the ordinary bacillus. On the other 

 hand, the susceptibility of Dieudonn(^'s frogs must depend on a less 

 resistance of the organism under the conditions of his experiments. 

 Unfortunately, we cannot find in his memoir sufficient data on these 

 points ; he does not even state the temperature at which the frogs 

 that had been inoculated with bacteria adapted to cold lived. 

 Dieudonne invokes the analogy of his results with those obtained 

 []49]in the case of the immunity and susceptibility of frogs as regards 

 a septicaemic bacillus. 



This bacillus (Bacillus ranicida) has been made the subject of 

 an interesting study by Ernst ^. It is a small, very slender bacillus, 

 which, in frogs, produces a fatal malady epidemic in spring, but 

 ceasing completely during summer. Taking this fact as a basis, 

 Ernst has succeeded in conferring immunity upon frogs in autumn 

 by placing them in an incubator at 25° C. In spite of the injection 

 of a considerable dose of the small bacillus, the frogs living at this 

 temperature remained in good health, whilst control animals exposed 

 to a low temperature died of septicaemia. The counter-test was 

 made in summer. Inoculated frogs that were kept in the laboratory 

 were unaffected, whilst those that had been kept in a refrigerating 

 apparatus at 6° — 10°C. invariably died. It may be asked, Is this 

 evident influence of temperature on immunity and receptivity exer- 

 cised on the organism of the frog or upon the pathogenic bacillus ? 

 In the case where a bacillus can only develop at low temperatures 

 its harmlessness at the higher temperature may be readily under- 

 stood. The experiments of Ernst have demonstrated, however, that 

 this small bacillus develops much better at 22° C, and even at 30° C, 

 than at lower temperatures. It must be concluded, therefore, 

 that the high temperature which confers immunity acts not by 

 1 Ziegler's Beitr. z.path. Anat, Jena, 1890, Bd. viii, S. 203. 



