XXI] PATHOGENIC ORGANISMS 541 



at a temperature of about 35° C, but also, only slower, 

 at ordinary temperature. Sattler cultivated 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 infusions 

 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 oedematous 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 un- 

 mistakably established that a harmless saprophyte, to wit the 

 bacillus mesentericus, 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 saprophyte 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 harmless being. The 

 theoretical and practical importance of such a case must be 



