86 



THE AMERICAN MONTHLY 



[May 



I 



12. If spores have formed, such 

 liquids may be kept at this tempera- 

 ture indefinitely, and retain their 

 original activity. 



13. Virulent liquids containing rods 

 alone, lose their activity when treated 

 with compressed oxygen. 



14. Such liquids in which spores 

 have formed, are not affected by this 

 agent. 



15. The virulence is also destroyed 

 by concentrated alcohol before spores 

 have formed. 



16. After spore-formation this agent 

 has no effect on the virulence. 



We have here a series of sixteen 

 facts, showing the connection be- 

 tween the activity of charbon-virus 

 and the presence of the living Bacil- 

 lus anthracis ; these facts have been 

 observed and confirmed by the most 

 accomplished investigators of the 

 time, and I take it for granted they 

 are entirely reliable. If they had 

 all been announced by one man, we 

 would be perfectly justified in mak- 

 ing certain reservations before accept- 

 ing them ; but when we have the 

 united testimony of such men as Koch, 

 Cohn, Buchner and Niigeli among 

 the Germans ; Pasteur, Toussaint and 

 Bert in France, and Greenfield in 

 England, it is not becoming to ex- 

 press doubts of their accuracy when 

 we have not even one scientific obser- 

 vation to support us. 



Accepting these observations as 

 facts, I maintain there is no longer 

 a shadow of doubt that the bacterium 

 in question is the essential cause of 

 the disease, and that it is the active 

 agent, and the only active agent in 

 the virus. 



This being the entering wedge for 

 the germ-theory in scientific patholo- 

 gy, it is perfectly right to demand 

 the most conclusive evidence before 

 admitting it ; but this evidence has 

 now been furnished — the germ-theory 

 has a substantial foundation — and 

 medicine is destined to make its most 

 brilliant triumphs by the discoveries 

 to which it will lead. The progres- 

 sive pathologist will waste no more 



time in criticising what is so well 



established, but will press onward to 



other and equally important disco 



eries. 



o 



Photographing Bacteria. 





The method of staining bacteria 

 for photographing, described in the 

 last number of this Journal (p. 53), 

 is doubtless an improvement upon 

 Koch's method of staining with anilin 

 violet, for, as there stated, the violet 

 gives very little photographic con- 

 trast, because it permits the actinic 

 rays to pass. A method which I have 

 employed with success, and which, so 

 far as I knov/, is new, is the follow- 

 ing :— 



The bacteria are dried upon a 

 slide or upon a thin glass cover, and 

 are then treated with commercial 

 sulphuric acid, a drop of which is 

 placed upon them. After two or 

 three minutes the acid is washed off 

 by a gentle stream of water, and the 

 bacteria are then covered with an 

 aqueous solution of iodine (iodine, 

 grs. 3 ; potassic iodide, grs. 5 ; water, 

 grs. 500). After a few minutes they 

 will be found to present a deep- 

 orange or brown color, which gives 

 the desired contrast in a photograph- 

 negative. I have only found this 

 method useful for extemporaneous 

 preparations which are to be photo- 

 graphed immediately. According to 

 my experience the color fades after 

 a time, and the bacteria undergo 

 changes in form (swelling) as a result 

 of this treatment, which renders the 

 method unsatisfactory when the ob- 

 ject is to make a permanent prepara- 

 tion. For this purpose I have found 

 nothing better than the anilin violet, 

 which, indeed, leaves nothing to be 

 desired when a collection is being 

 made without reference to photo- 

 graphy. I am in the habit of mount- 

 ing my speciments either in solution 

 of acetate of potash (Koch's method) 

 or in carbolic acid water, and I pre- 

 fer the last named fluid. 



Anilin violet ink, which may be 



