158 G. C. KAROP OX A SPECIMEN OF BACILLUS TUBERCULOSUS 



sumption is characterised by a special organism or bacillus, a speci- 

 men of which I have the honour of submitting to your notice this 

 evening. 



The first thing that may strike the observer who has any ac- 

 quaintance with these low forms, is, how can it be possible to differ- 

 entiate as special organisms, what for the most part are but spots 

 or rods under even the highest powers ? and after reading Tyndall's 

 " Floating matter in the air," and knowing how universally present 

 such organisms are in the lower strata of the atmosphere, one is 

 apt to be rather sceptical in such a case as the present, and to in- 

 cline to the opinion that although bodies are undoubtedly present, 

 they are mere products of decomposition, or other accidental 

 phenomena. 



This, however, is met by the curious fact that certain forms are 

 selective of certain anilin dyes, and are capable of being stained 

 only by such colours, and it is entirely a matter of experiment to 

 ascertain the affinities any form may possess. As to how far this 

 may be the case, and on what it depends, whether on the presence or 

 absence, or density of envelope or what not, can only be determined 

 by experience ; remembering too when so many experiments are 

 being made and so many methods employed, contradictions and 

 mis-statements are sure to be made, and it is only by patient and 

 repeated observation that any definite opinion can be arrived at. 

 For instance, in the present case. Dr. Koch's method of showing 

 the bacillus, was difficult, tedious, and uncertain. It was inrproved 

 by Dr. Ehrlich, his assistant, but his procedure, too, gave uncertain 

 results, and was very complicated. It is described in the last 

 number of the " Journal of the Royal Microscopical Society." 



Finally, Dr. Heneage Gibbes, of King's College Hospital, has 

 invented a process whereby the bacillus, if present, can be shown, 

 with comparative ease and but little trouble. The method he 

 employs is given at length in the Lancet, of Aug. 5th, but as 

 some here may not have seen his description, and would wish to know 

 it, I subjoin a short resume of the process. 



The necessary reagents are as follows : — A solution of magenta 

 in pure anilin, this is the stain. A solution of chrysoidin in water, 

 to which a little thvmol is added, and some common nitric acid, one 

 part to two of water. A small portion of the suspected sputum 

 is spread very thinly on a cover-glass and allowed to dry perfectly, 

 it is then passed through a spirit flame once or twice to ensure its 



