184 THE AMERICAN MONTHLY [June 



him and Dr. Bowerbank, who could not avoid giving so 

 home a trust as to remind liim of it. Even after it was 

 generally allowed that they belonged to the animal king- 

 dom, a reservation was made for sometime before the 

 fresh- water sponges were placed in the same position. 

 Observers could not have seen, as I have, the blow-fly 

 hovering over and depositing its eggs, attracted doubt- 

 less, by the offensive odor of decomposing flesh. 



How the Bacterial Organisms are Studied. 



By J. E. LAMB, M. D., 

 WAHOO, NEBR. 



The technique of investigating these microscopic plants 

 is manifold. Microscopy alone is inadequate. Identifi- 

 cation requires other tests than those afforded by the 

 microscope. 



These tests are : — 1. Staining agents. 2. Appear- 

 ance of cultures. 3. Reaction to heat and oxygen. 4. 

 Pathogeny. 



1, Staining agents. — Watery solution of the aniline 

 dyes penetrates the protoplasm in the cell bodies of most 

 bacteria, yet the tubercle bacillus long eluded observa- 

 tion because it absorbs the solution only when the water 

 is reinforced by some other agent like carbolic acid or 

 alcohol. This microbe is stained with great difficulty, 

 but once stained, it is very resistant to decolorizing 

 agents. Upon these facts, all staining solutions and 

 methods of staining are founded. Some operate slowly, 

 others more rapidly. 



In order to appreciate and differentiate the tubercle 

 bacillus, the following solutions and methods of use, are 

 more easy and simple to manipulate than any others with 

 which the writer is acquainted. It is hoped they may 

 prove as acceptable as those you are now using. 



