40 



so on ad libitum ; indeed, the mere contact with a fresh 

 wound of a scalpel-point previously dipped in the septic 

 blood sufficed. Here, then, was something entirely dif- 

 ferent from the intoxication following injection of a larger 

 quantity (five to ten drops) differing in the existence 

 of a marked stage of incubation, of local reaction, and in 

 certain and uniform infectiousness. The blood of such an 

 animal evidently contained something not present in 

 that of the former mouse a something requiring time for 

 the manifestation of its influence, and finally distributing 

 itself throughout the entire blood-mass, so that each drop 

 thereof possessed the septic possibilities of the original 

 putrid drop. Such mode of action implies reproduction, 

 and reproduction is a characteristic of organized matter. 

 It was to be expected a priori, therefore, that the blood 

 contained organisms ; Koch found, in fact, invariably, 

 that the blood serum, white blood-corpuscles, and various 

 tissues of such animals swarmed with minute rods, which 

 stained readily with aniline colors, and when removed 

 from the body into similar artificial conditions multi- 

 plied by transverse fission. Since the blood of the in- 

 fected and infecting mouse differs evidently from that 

 of the intoxicated and non-infecting mouse only in the 

 presence of these bacteria, Koch ascribes the infectious- 

 ness to these organisms. It is interesting to note that 

 all attempts to inoculate rabbits and field-mice with 

 the septic blood were fruitless. The animals remained 

 unaffected ; no bacilli were found in their blood, al- 

 though the mouse-blood used for inoculation was full 

 of them. Further, that although the putrid fluids in- 

 jected contained organisms of numerous varieties micro- 

 cocci, bacteria, bacilli all of which were subsequently 

 found in the local oedematous liquid, yet only one spe- 

 cies, the minute bacillus, was found distributed through- 

 out the blood and tissues. The living mouse seemed to 

 be a culture-medium for isolating these from the other va- 

 rieties, to whose growth the animal's tissues were less 

 perfectly adapted. In the second or third mouse suc- 

 cessively inoculated only the specific bacilli were found. 



