1891.] Proceedings of Scientific Societies. 89 
Dr. Theobald Smith spoke of ‘‘Species among Bacteria.” He 
stated it to be possible to separate and study the various forms in a 
nutrient fluid. The species or forms can be separated by both morpho- 
logical and biological characters. Among the former were enumer- 
ated form, size, formation of spores, method of germination, flagella, 
and staining. The biological characters are the results of culture, 
both in liquid and upon solid media, The forms can be distinguished 
by habitat, by the formation of ferments which liquify gelatine, by 
fermentation, by affinity for oxygen, by coloring matter, and by their 
occurrence in disease. 
As examples of these differences the bacillus of anthrax and of hay 
were compared. They were long supposed to be closely related, and 
under the microscope both look alike, both grow in the same way, and 
both have spores of the same kind. But when the two are cultivated in a 
liquid the hay bacillus will form a scum upon the top of the liquid in a 
short time ; the liquid will then become cloudy throughout, and finally 
clear up. With the anthrax, on the contrary, the cloud makes its 
appearance at the bottom of the culture tube. In germination of the 
spores, the anthrax grows in the direction of the larger diameter, while 
the other grows at right angles to it. If the hay bacillus be placed 
under the skin of an animal, it is innocuous. But if the anthrax be 
injected, it will kill in twenty-four hours. 
gain, in the typhoid fever and the hog cholera bacillus there is 
great similarity in morphological characters ; but when cultivated they 
assume different colors. In the fermentation tube hog-cholera germ 
evolve gases, while the typhoid do not. One form of the comma ba- 
cillus cultivated on gelatine liquifies it; another similar form does 
not. 
In the discussion Mr. True thought the morphological characters 
were those which characterized higher groups than species ; they were 
rather family, perhaps ordinal, characters. Dr. Smith, in replying 
to this, stated that it was impossible to say what were family, 
what were generic, what were ordinal characters, but those he had 
mentioned were of use in distinguishing the various forms one from 
another. 
[In the course of the discussion the fact that the organisms under 
consideration were of vegetable rather than animal nature was lost 
sight of. While, therefore, the morphological characters of form, size, 
Spores, etc., referred to would not do to separate species of animals, 
they are exactly the characters used by botanists to separate species of 
plants, Dr. Smith, therefore, in stating that species could be separated 
