xvii.] SEPTIC AND PATHOGENIC ORGANISMS. 161 



cent., this infusion after some hours to a few days contains 

 numerous bacilli, motile, capable of forming spores, and in all 

 respects identical with a bacillus subtilis. The bacilli are 

 about 0-00058 mm. thick, and from 002 to 0'0045 mm. long. 

 They form a pellicle on the surface of the infusion, and in the 

 bacilli of this pellicle active spore formation is going on. The 

 bacilli grow and multiply well at a temperature of about 35 C., 

 but also, only slower, at ordinary temperature. Sattler culti- 

 vated artificially the bacilli on blood-serum gelatine and meat- 

 extract peptone gelatine, both solid media, and continued their 

 growth through several successive cultivations. Both the in- 

 fusions of the jequirity and the bacilli taken from these 

 artificial cultures inoculated into the conjunctiva of healthy 

 rabbits produce severe ophthalmia, leading to the production 

 of great redematous swelling of the conjunctiva and eyelids, 

 and temporary closure of the latter, and to the secretion of 

 purulent exudation. Both the exudation and the swollen lids 

 are said to contain infective bacilli and their spores. Sattler 

 ascertained by many experiments, that none of the bacilli and 

 the spores distributed in the atmosphere had those specific 

 properties, viz., to excite ophthalmia, as long as they grow in 

 other than jequirity fluid, but having had access, i.e. having 

 entered the jequirity infusion, assume here this specific power. 

 There is no doubt that Sattler worked the whole problem with 

 great care, worked out all points connected with it in great 

 detail, and for this reason his work was considered to have 

 for the first time unmistakably established that a harmless 

 bacillus, owing to the particular soil in which it grew, assumes 

 definite specific or pathogenic properties. To me this jequirity 

 bacillus had a great interest, since I was particularly anxious 

 to get hold of such an organism, in order to see whether and 

 how far it can again be made harmless. For if ever there was 

 a good case, a case in which a previously harmless micro- 

 organism had by some peculiar conditions become specific, 

 this was a case ; and therefore it must be here possible by 

 altering its conditions of life again to transform it into a harm- 

 less being. The theoretical and practical importance of such 

 a case must be evident to every one who has at all devoted 

 any thought to the relation of micro-organisms with disease. 

 The whole doctrine of the infectious diseases, I might almost 

 say, is involved in such a case, for if in one case it can be 

 unmistakably proved that a harmless bacterium can be trans- 

 formed into a pathogenic organism, i.e. into a specific virus of 

 an infectious malady, and if this again can under altered 

 conditions resume its harmless property, then we should at 



