364 DIPHTHERIA. 



cultures or in membrane, they have a low power of resistance,, 

 being killed at 60° C. in a few minutes. On the other hand, in 

 the dry condition, they have great powers of endurance. In 

 membrane which is perfectly dry, for example, they can resist a 

 temperature of 98° C. for an hour. Dried diphtheria membrane, 

 kept in the absence of light and at the room temperature, has. 

 been proved to contain diphtheria bacilli still living and virulent 

 at the end of several months. The presence of light, moisture, 

 or a higher temperature, causes them to die out more rapidly. 

 Corresponding results have been obtained with bacilli obtained 

 from cultures and kept on dried threads. These facts, especially 

 with regard to drying, are of great importance, as they show that 

 the contagium of diphtheria may be preserved for a long time 

 in the dried membrane. 



Effects of Inoculation. — In considering the effects produced 

 in animals by experimental inoculations of pure cultures, we have 

 to keep in view the local changes which occur in diphtheria, and 

 also the symptoms of general poisoning. 



Loffler in his original paper stated that in the case of rabbits, 

 guinea-pigs, pigeons, and fowls, the bacilli taken from pure 

 cultures produced no change on healthy mucous membranes, but 

 when the latter were injured by scarification or otherwise, inocula- 

 tion caused the formation of false membrane. A similar result 

 was obtained when the trachea was inoculated after tracheotomy 

 had been performed. In this case the surrounding tissues 

 became the seat of a blood-stained oedema, and the lymphatic 

 glands were enlarged, the general picture resembling pretty 

 closely that of laryngeal diphtheria. These results have been 

 amply confirmed by other observers. The membrane produced 

 by such experiments is usually less firm than in human diphtheria, 

 and the bacilli are not generally found in such large numbers in 

 the membrane. Rabbits inoculated after tracheotomy often die, 

 and Roux and Yersin were the first to observe that in some 

 cases paralysis may appear before death. 



Subcutaneous injection, in guinea-pigs, of diphtheria bacilli 

 in a suitable dose, produces death within thirty-six hours. On 

 section at the site of inoculation there is seen a small patch of 

 greyish membrane, whilst in the tissues around there is exten- 

 sive inflammatory oedema, often associated with haemorrhages, 

 and there is also some sweUing of the corresponding lymphatic 



