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genes, B. Cloace, and Oxytocus perniciosus, more especially 
by those of the proteus group. It is not given constantly by 
all bacilli of these groups, although, it is apparently a very 
constant and excellent confirmatory test for B. Cloace and 
Oxytocus perniciosus. It is not apparently so good a test for 
B. Lactis erogenes as stated by MacConkey.’’ With this 
last remark we agree, but for the other organisms the reaction 
appears to us to be a very satisfactory test, if certain simple 
precautions, such as, adding a fair quantity of the culture to 
the glucose broth, incubating for 48 hours or more, are always 
observed. Some care has to be exercised, as in all similar 
reactions, for in some instances the colour is rather faint. If, 
however, a very small quantity (2 or 3 drops) of a saturated 
solution of caustic potash is used, instead of a large quantity of 
dilute solution, the amount of fluid in the tube is not increased, 
and the colour very seldom fails to appear in sufficient quan- 
tities to be easily recognisable in two hours. B. Lactis 
erogenes loses its power to give the reaction under the 
influence of sunlight, but recovers it again if it is cultivated 
in laboratory media. 
(3) Motility —On the subject of motility as a constant 
characteristic of any organism opinion is again divided. Ad- 
mitting, for the sake of argument, that motility is a perfectly 
constant character of a given species of bacillus, in other words, 
a motile organism possesses cilia and a non-motile one does not, 
it nevertheless is certain that a bacterium that is really motile, 
may be found at times with loss of motility which can be easily 
restored to it by culturing it. If the work of this report had 
for its object the solution of purely bacteriological problems, 
then all non-motile organisms would be cultured two or three 
times in broth in order to ascertain if this characteristic had 
been temporarily lost. But for routine work this is out of the 
question, consequently we recommend that motility be care- 
fully looked for once, viz., after 18 hours’ cultivation in broth, 
but that when a negative result is obtained too much impor- 
tance be not attached to the result, as there can be no doubt 
that this test is not of the same order of importance as the 
power to ferment a sugar, or alcohol. We have some experi- 
ments which tend to show that an organism loses its power of 
