464 



Mr. G. F. Dowdeswell. 



[Jan. 18, 



repeated. In the former trials, where inoculations were made under 

 antiseptic spray, both in the tubes of bouillon and of serum, acci- 

 dental contaminations sometimes occurred. In the present experi- 

 ments, inoculations were made through sterilised cotton wool, which 

 is the only reliable method of artificial cultivation with which I am 

 acquainted, and which I have found in numerous experiments, even 

 with such unstable substances as blood serum, to be absolutely in- 

 fallible, with moderate care in manipulation. It was communicated 

 to me by Dr. E. Klein, and is, I believe, described by him in detail 

 elsewhere. The infective exudation serum used for inoculation in 

 this case was from a guinea-pig, in which it had been produced by 

 the subcutaneous injection of a few drops of the serous fluid in 

 infective peritonitis, artificially induced : the organisms herein were 

 not very numerous, consisting chiefly of short rods of somewhat 

 variable breadth, one end being frequently swollen, as in the forma- 

 tion of spores, distinct forms of which, however, were not apparent, 

 though cell-rods, in a very early stage of development, were. It at 

 first seemed as if there were here two distinct species of Bacilli 

 present, but subsequent observations showed that they were only 

 forms of one and the same in different stages of development. The 

 narrower cells were, in fact, degenerating and withering, which 

 frequently accompanies spore formation, the cell presenting a 

 shrivelled and somewhat contorted figure instead of the usual uni- 

 formly cylindrical sharp contour. This stage is more frequently and 

 readily seen in artificial cultivation outside the animal body. The 

 tubes containing sterilised blood serum and beef bouillon being 

 inoculated with a small particle of this fluid, were then exhausted of 

 air, sealed, and placed in the incubator, when the next day their 

 incipient turbidity showed that vegetation was proceeding readily; 

 on the second they were opened, and both the serum and bouillon* 

 were found to be full of the same species of Bacilli originally inocu- 

 lated, in various stages of development, forming numerous and distinct 

 spores. More than one tube of each nutritive medium was always pre- 

 pared, and it was observed in those containing serum that the more 

 solid it had become by evaporation the more slowly did the vegetation 

 progress in it, rendering it fluid as it proceeded. On opening the tubes 



* Blood serum offers a suitable cultivating medium for probably all pathogenic 

 organisms ; it is easily sterilised, and when once this is effectually done, it may be 

 kept for any length of time, and while remaining perfectly translucent may be 

 rendered by prolonged heating of any consistency required. Koch's method of 

 gelatine culture, though most valuable for particular purposes, is not for several 

 reasons suitable for use generally in these experiments. With the exception of JB. 

 anthracis most pathogenic bacteria, as distinguished from the merely septic, vegetate 

 sparsely if at all in vegetable infusions, the attempts to cultivate them in which are 

 generally disappointing and misleading. 



