SCIENCE. 



561 



branes they were almost as numerous as in the diphther- 

 itic exudation. 



Last spring we resumed our investigations. Having 

 heard that there was a very severe epidemic in Luding- 

 ton, Mich., Dr. Formad was dispatched to examine cases 

 and collect material. He found a small town situated 

 upon the shore of Lake Michigan, in the centre of the 

 lumber region, with inhabitants mostly engaged in the 

 lumber trade and in managing very numerous large saw- 

 mills. The town was all built upon high ground except 

 the Third Ward. This occupied a low swamp which 

 had been filled in largely with sawdust. The soil was so 

 moist that a hole.dug in it would fill at once with water, 

 and but few houses had any attempts at cellars. It was 

 in this district that the disease had "prevailed. Almost 

 all the children had had it, and one-third of them were 

 said to have died. Dr. Formad examined a large number 

 of cases, obtained a supply of diphtheritic membrane, 

 and brought home pieces of the internal organs of a 

 child upon whom he had made an autopsy. In every 

 case the blood was found more or less full of micrococci, 

 some free, others in zooglcea masses, others in the white 

 blood-corpuscles. The organs brought home also all 

 contained micrococci, which were especially abundant in 

 the kidneys, where they formed numerous thrombi, chok- 

 ing up and distending the blood-vessels. In the summer 

 of 1880 we examined the blood of several cases of ende- 

 mic Philadelphia diphtheria, and in no case found any 

 new elements in it. But during the present summer we 

 have found micrococci in the blood of Philadelphia diph- 

 theritic patients, showing the differences in the disease 

 are simply in degree, not in kind. 



Experiments were now made with the Ludington 

 material upon animals. Inoculations were practised un- 

 der the skin, deep in the muscles, and in the trachea. 

 In all cases the results were similar. A grayish exuda- 

 tion appeared at the seat of inoculation, along with much 

 local inflammation, the animal sickened, and in the 

 course of a few days death occurred. The local symp- 

 toms increased and wide'ned. In some cases the false 

 membrane spread from where the poison had been put in 

 the trachea up to the mouth. The blood examined dur- 

 ing life or after death was found to contain micrococci 

 precisely similar to those found in the Ludington cases, 

 and in a few instances nvcrococci were found in abund- 

 ance in the internal organs. Studies made upon the 

 blood of these animals, as well as upon the Ludington 

 cases, show that the micrococci first attack the white 

 blood-corpuscles, in which they move with a vibrat'le 

 motion. Under their influence the corpuscles alter their 

 appearances, los'ng their granulations. They finally be- 

 come full of the micrococci, which now are quiescent, 

 and increase until the corpuscle bursts and the contents 

 escape as an irregular, transparent mass full of micro- 

 cocci, and form the so-called zoogloea masses. In the 

 diphtheritic membrane the micrococci exist frequently in 

 balls, and it is plain that these collections are merely 

 leucocytes full of the plant. The bone-marrow of the 

 animals were found full of leucocytes and cells contain- 

 ing micrococci. 



The question now arose, is the disease produced by 

 diphtheritic inoculation in the rabbit diphtheria ? We 

 concluded that it is, because the poison producing it is 

 the same, the symptoms manifested during life ate the 

 same, and *he post-mortem lesions are identical. The 

 contagious character of the disease is retained, as we 

 succeeded in passing it from rabbit to rabbit. 



Our next series of experiments were directed to deter- 

 mining whether the micrococci are or are not the cause 

 of the affection. The experiments ot Curtis and Satter- 

 thwaite, of New York, have shown that the infectious 

 character of diphtheria depends upon its solid particles ; 

 for when they filtered an infusion of the membrane it 

 became less and less toxic in proportion as the filtration 

 was more and more perfect ; and when the infusion 



was filtered through clay, the filtrate was harmless. 



The urine of patients suffering from malignant diph- 

 theria is full of micrococci, and may contain no other 

 solid material. Following the experiments of Letzerich, 

 we filtered this urine and then dried the filter-paper. 

 Upon experiment we found this even more deadly in its 

 effects than is the membrane. The symptoms and lesions 

 following in the rabbit inoculation with such paper are 

 precisely those which would have ensued had a piece of 

 diphtheritic kidney or membrane been employed. This 

 experiment shows that the solid particles of the mem- 

 brane, which are the essential poison of malignant diph- 

 theria, are the micrococci, which must be either the 

 poison itself or the carriers or producers of the poison. 



Leaving for a while this point, I will next direct your 

 attention to our culture-experiments. These were per- 

 formed in the manner commenced by Klein and that 

 recommended by Sternberg. The first method seems to 

 us the best for the purpose of studying the development 

 of the micrococcus itself; the second the best for the ob- 

 taining of it in quantity for experimentation. 



We cultivated micrococci from the surface of ordinary 

 sore throats, from furred tongue, from cases ol mild 

 diphtheria as we commonly see it in Philadelphia and 

 from Ludington cases. We found, in the first place, 

 that there were no differences to be detected in the gen- 

 eral or special appearance of the various micrococci, and 

 no constant differences in size. We found that they all 

 formed similar shapes in the culture apparatus ; they 

 had this difference, however, — whilst the Ludington mi- 

 crococci grew most rapidly and eagerly generation after 

 generation up to the tenth, those from Philadelphia diph- 

 theria ceased their growth in the fourth or fifth genera- 

 tion, whilst those taken from furred tongue never got 

 beyond the third transplantation. Various culture-fluids 

 were used, but the results were identical. We conclude, 

 therefore, that as no difference is detectable between the 

 micrococci found in ordinary sore throat and those of 

 diphtheria, sive only in their reproductive activity, they 

 are the same organisms in different states. As the result 

 of some hundreds of cultures, we believe that the vital- 

 ity of the micrococci under artificial culture is in direct 

 proportion to the contagious powers of the membrane 

 from which they have been taken. We have made 

 many inoculations with cultivated micrococci and have 

 succeeded in producing diphtheria with the second 

 generation, but never with any later product. This suc- 

 cess, taken in conjunction with the urine experiments 

 already spoken of, seems to us sufficient to establish the 

 fact that the micrococci are the fons et origo malt of 

 diphtheria. The experiments of Pasteur and others 

 have proven that it is possible for an inert organism to 

 be changed into one possessed of most virulent activity, 

 or vice versa, and we believe that we can offer direct 

 proof that the micrococci of the mouth are really iden- 

 tical in species with the micrococci ot diphtheria, and do 

 not merely seem to be so. We exposed the Ludington 

 membrane for some weeks io the air in a dried condi- 

 tion. There was no putridity or other change detectable 

 in it ; but, whereas formerly it had been most virulent, 

 now it was inert, and its micrococci not only looked 

 like those taken fiom an ordinary angina, but acted like 

 them. They were not dead, they had still power of 

 multiplication, but they no longer grew in the culture- 

 fluid beyond the third or fourth generation. Certainly 

 they were specifically the same as they had been, and 

 certainly therefore the power of rapid growth in culture- 

 fluids and in the body of the rabbit is not a specific 

 character of the diphtheria micrococcus. 



As is well known, Pasteur attributes the change from 

 an active to an inert organism to the influence of the 

 oxygen of the air upon the organism. Whether this be 

 true or not of the diphtheria micrococcus is uncertain, 

 but the effects of exposure of the dried membrane seem 

 to point in such direction. 



