74 G. F. DOWDESWELL. 



occurs cannot be regarded as conclusively shown. I have found 

 quite recently that living Bacteria may be stained by a solution 

 of Bismark brown, which does not appear to have a toxical effect 

 upon these organisms as other aniline dyes have ; by its action 

 spores developing within the Bacilli are conspicuously differen- 

 tiated. By tins means, in conjunction with the method recently 

 described by Dr. Koch of adding gelatine to the nutrient fluid, 

 their cultivation and further study will no doubt be facilitated. " 



1 have not succeeded in transmitting specific septicsemia by 

 inoculation from one animal to another of a different species, 

 notwithstanding numerous experiments. Dr. Koch, I under- 

 stand, has done so, and finds in the blood of pigeons infected 

 from another animal a totally distinct form of Schizophyte, 

 a small micrococcus of characteristic appearance, morphologically 

 identical, I believe, with the microbe of Pasteur's cholera des 

 ponies, and which Dr. Koch regards as the specific contagium, 

 the true cause of the disease. This, however, appears to me to 

 involve a direct contradiction, or the occurrence of distinct 

 heterogenesis in the Schizophyte, for the doctrine that the 

 various forms of these organisms are but different phases of one 

 and the same species, modified by external conditions, though 

 a view which is supported by the high authority of von Niigeli, 

 yet lacks experimental evidence. Others, again,^ have recently 

 asserted that by cultivation in different media, through several 

 generations, a transformation of physiological species has been 

 effected, so that what is at one time a perfectly harmless form, 

 and universally diffused, becomes the virulent contagium of 

 infective disease. These results, though accepted by some, as 

 by Prof. Virchow, are regarded as erroneous by a very high 

 authority on this subject, M. Pasteur, whose brilliant results, 

 together with those of M. Toussaint, in Prance, and others,^ on 

 the methods of preventive inoculation, now well known, have 

 lent a new and practical importance to the subject, and demon- 

 strated a possible beneficent function of these organisms, more 



^ Dr. Hans Biichner, in the ' Sitz. Bericht. d. math, phys., Classe d. K. 

 B. Akad. d. Wissens. zu Miinchen,' H. iii, 1880, asserts the trausforma- 

 tion iu artificial cuUivation of the £. anthracis into the hay Bacillus, and 

 also the converse change. Ingenious and laborious as his methods are, they 

 are defective, and the admitted occurrence of contaminations throughout, 

 in the cultivations, ou the purity of which tlie whole question at issue 

 depends, entirely invalidates his conclusions. Dr. Grawitz, in ' Virchow's 

 Archiv,' Bd. 81, and in some previous journals, records experiments with 

 the Hypomycetes to a similar effect. 



2 In this country. Dr. Burdon Sanderson and Mr. Duguid, ' Jouru. R. 

 Agric. Soc.,' 2 ser., V. xvi ; Dr. Greenfield, ' Proc. R. Soc.,' V. xxx, p. 150 ; 

 and ' Journ. R. Agric. Soc.,' 2 ser., V. xviii, pt. 1. 



