NOTES ON MICRO-ORGANISMS. , 31 
give very good specimens, and the slides can easily be cleaned 
afterwards if desired. During the last few days I have tried 
staining with Eosine, used according to the methods for other 
dyes. It seems to give excellent results; in fact, I should say 
better than magenta or methyl violet, the defining densities of the 
protoplasm being shown very clearly. 
Some very artistic effects have been produced by double stain- 
ing, where organisms are present with tissues of other substances. 
The first colour used is removed from the tissues, but not from 
the organisms, by nitric acid or alcohol, and after removal of 
these last a contrast colour is run on. I have noticed that Bac- 
teria will often show active movements even when they have been 
dried off at roo degrees Fahrenheit, and stained quite deeply. 
An extract of logwood is said to be useful for staining cell 
envelopes and the Flagella. It is sometimes convenient to treat 
drops of liquid or tissues containing Bacteria on a thin cover-glass, 
instead of on a glass slip. 
Hitherto we have almost exclusively dealt with Micro-organisms 
that, with the exception of a septic effect on wounds, do not 
appear to have any poisonous action in the human body, for every 
day we take in myriads of them with air, food, etc., and in the 
main do not seem any the worse for it; and, indeed, it is a 
question whether some of the changes that food undergoes in the 
system, necessary to its conversion into easily assimilable matter, 
are not facilitated by the presence of organisms. On the other 
hand, there can be no reasonable doubt that certain maladies and 
diseases have their origin in so-called Pathogenic Bacteria. This 
is certainly the case in erysipelas, anthrax fever, glanders, and 
tuberculosis; whilst in the case of blood-poisoning, diphtheria, 
relapsing fever, small-pox, typhoid, and a considerable number of 
other diseases, including cholera, there is good reason to believe 
that the micro-organism associated is the causal agent, always 
presuming that the human body has by some means become pre- 
disposed to the growth of the organism involved (Plate III, Fig. 4, 
and Plate IV., Figs. 3, 4, 5, 6). ~The spherical bodies in Figs. 4 
and 6 are blood corpuscles. 
