DIPHTHERIA. 295 



indeed we have ample evidence that certain or- 

 ganisms demonstrated to have pathogenic proper- 

 ties do not differ in form from others known to be 

 harmless. 



The elaborate and carefully conducted inves- 

 tigations of Wood and Formad, made under the 

 auspices of the National Board of Health, give 

 support to the view that the micrococcus found by 

 them in diphtheritic exudations is the infectious 

 agent in this disease. 



In an editorial in the "Medical Times" (April 

 22, 1882), Dr. Wood says :- 



" A number of experiments were made upon the 

 effect of boiling the membrane, and it was found that if 

 the heat were maintained for only four or five minutes 

 the contagious power was not always destroyed, but 

 that when the boiling was continued for fifteen minutes 

 or longer, inoculation with the virus always failed to 

 produce any local or general effects. Culture experi- 

 ments with this innocuous virus showed that the boil- 

 ing had killed the micrococci, which entirely refused to 

 grow. It is scarcely necessary to point out the con- 

 firmation this lends to the belief that the micrococci are 

 the materies morbi. . . . 



"A number of cultures were also made, and inocula- 

 tions with the liquid practised. In six or eight in- 

 stances the second, third, or fifth generation of cultured 

 plants caused the death of the rabbit. In all these 

 cases micrococci were abundant in the blood and inter- 

 nal organs. In some animals the local exudations were 

 marked, and resembled those of diphtheria ; but in other 

 rabbits the local symptoms were only slight swelling 

 and infiltration of the surrounding tissues with serous 



