A Contribution to the Etiology of Diphtheria. 71 



May 22, 1890. 

 Sir G. GABRIEL STOKES, Bart., President, in the Chair. 



The Presents received were laid on the table, and thanks ordered 

 for them. 



The following Papers were read : 



I. " A Contribution to the Etiology of Diphtheria.'-* By 

 E. KLEIN, M.D., F.R.S. Received April 25, 1890. 



The microbe, which was first described by Klebs (at the Wiesbaden 

 Congress in 1883), then isolated and grown in artificial cultures by 

 Loftier ('Mitth. aus dem K. Gesnndheitsamte,' vol. 2) from human 

 diphtheritic membrane, was shown by this observer to act virulently 

 on various animals. The Klebs-Loffler bacillus by which name the 

 diphtheria microbe is known is the one with which also Roux and 

 Yersin (' Atmales de 1'Institut Pasteur,' vol. 2, 1888, No. 12) obtained 

 positive results on guinea-pigs. 



In the Reports of the Me.iical Officer of the Local Government 

 Board for 1888-1889 and 1889-1890, I have shown that there occur 

 in diphtheritic membranes two species of bacilli, very similar in 

 morphological respects, and also in cultures on serum and on agar, 

 but differing from one another in this, that one species, Klebs-Loffler 

 bacillus No. 1, is not constant in diphtheritic membranes, does not 

 grow on solid gelatine at 19 20 C., and does not act pathogenically 

 on animals ; the other species, Klebs-Loffler bacillus No. 2, is constant 

 in diphtheritic membranes, in fact is present even in the deeper layers 

 of the membranes in great masses and almost in pure culture, acts 

 very virulently on animals, and grows well on gelatine at 19 20 C. 

 Loffler, and after him other observers (Flvigge, ' Die Mikroorganismen,' 

 1886), considered it as a character of the diphtheria bacillus that it 

 does not grow on gelatine below 22 C., but this character, though 

 true of the Klebs-Loffler species No. 1, does not appertain to the 

 diphtheria bacillus species No. 2. In fact, there is no difficulty in 

 obtaining pure cultures of this bacillus on gelatine if a particle of 

 diphtheritic membrane be taken and well shaken in two or three 

 successive lots of sterile salt solution, and from the last lot plate 



* This research was undertaken for the Medical Deirtment of the Local 

 Government Board, and is communicated to the Royal Society with the permission 

 of the Medical Officer. 



