ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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(4) Tetracocci, double-celled diplococci. Length of a double cell 
about 1*5/4, thickness 1 /x. The diplococci may be connected in pairs 
or chains or heaps. Tetracoccus butyri grows well on the usual media, 
does not liquefy gelatin, or exhibit any movements. It acidulates milk, 
but does not coagulate it. 
(5) Bacillus butyri ii. is 1-2 /x thick, 3-6 /x long, forms a whitish 
growth on gelatin, which it does not liquefy. In bouillon drop cultiva- 
tions, movements were observed. 
All the five organisms grew well at 20°-35° C. They stained well 
with methyl-violet, fuchsin, &c., but were decolorized by Gram’s method. 
Inoculations on animals were negative. 
Streptococci.* — According to Dr. A. Pasquale, Streptococci cannot 
be differentiated into species, and he suggests the following basis for 
their natural classification : — 
(1) Short saprophytic streptococci. 
a. Growing at low temperatures, e. g. those of fasces and external 
environment. 
b. Those of mouth and respiratory mucosa. 
(2) Long non-virulent streptococci. 
a. Faecal, e. g. S. coli gracilis. 
b. From oral mucosa (Kruse and Pansini). 
(3) Long pathogenic streptococci. 
a. Erysipelas, pus, pneumonia, diphtheria, scarlatina. 
b. Pneumonic sputum. 
(4) Short highly infectious streptococci. 
a. Tuberculosis, &c. ( JDiplococcus 'pyogenes). 
b. Pneumonia (D. pneumonise'). 
This classification is not intended to draw sharp lines of demarcation 
between streptococci, but on the contrary, to indicate the natural con- 
nection existing between them. 
The most important criteria for the differentiation of streptococci 
may be obtained from the microscopical and cultural appearances in 
alkaline bouillon, as in this medium the characters of streptococci are best 
brought out. When cultivated in different kinds of serum it was noted 
that in rabbit serum the same streptococcus throve well, badly, or did 
not develope at all, according to the individual from which the medium 
was derived ; and the author also records another interesting fact about 
streptococci which produce septicaemia in rabbits, viz. that these may 
generate a blood-red pigment when the nutritive medium is suitable and 
oxygen absent. 
Experiments as to the pathogenic properties of streptococci were 
made on mice and rabbits by injecting into abdominal cavity or sub- 
cutaneously fresh bouillon cultivations. In some cases a fatal issue 
was attended by presence of the streptococci in the blood, in others, the 
organisms were found in the viscera, but not in the blood, while in 
others death did not take place. 
In the first group the most poisonous cultures were found to be 
* Beitr. z. Pathol. Anat. u. z. Allgem. Pathol., xii. pp. 433-93. See Centralbl. f. 
Eakteriol. u. Parasitenk., xv. (1894) pp. 761-4. 
