mination (see pages 428 to 431).

NOTE.--The B. coli communis, derived from the alvine
discharges of the cow, is almost universally present in
large or small numbers, in retail milk. Its detection,
therefore, unless in enormous numbers, (when it indicates
want of cleanliness), is of little value.

~2. Vibrio Cholerae.~--Inoculate tubes of peptone water by using the same
amounts as in the search for members of the Coli-typhoid groups (_vide
ante_ 1-3); incubate aerobically at 37 deg. C. and complete the
examination as detailed under the corresponding section of water
examination (see page 439).

~3. B. Enteritidis Sporogenes.~--Inoculate tubes of litmus milk with
similar amounts to those used in the previous searches, omitting tube
No. 1 (_vide ante_ 1-3) place in the differential steriliser at 80 deg.
C. for ten minutes and then incubate anaerobically at 37 deg. C. for a
maximum period of forty-eight hours. Complete the investigation as
detailed under the corresponding section of water examination (see
page 438).

~4. B. Diphtheriae.~--

(A) 1. Plant three sets of serial cultivations, twelve tubes in each
set, from (a) cream C^{2}, (b) deposit D^{1} upon oblique
inspissated blood-serum, and incubate at 37 deg. C.

2. Pick off any suspicious colonies which may have made their appearance
twelve hours after incubation, examine microscopically and subcultivate
upon blood-serum and place in the incubator; return the original tubes
to the incubator.

3. Repeat this after eighteen hours' incubation.

4. From the resulting growths make cover-slip preparations and stain
carbolic methylene-blue, Neisser's method, Gram's method. Subcultivate
such as appear to be composed of diphtheria bacilli in glucose peptone
solution. Note those in which acid production takes place.

5. Inoculate guinea-pigs subcutaneously with one or two cubic
centimetres forty-eight-hour-old glucose bouillon cultivation derived
from the first subcultivation of each glucose fermenter, and observe the
result.

6. If death, apparently from diphtheritic toxaemia, ensues, inoculate two
more guinea pigs with a similar quantity of the lethal culture. Reserve
one animal as a control and into the other inject 1000 units of
antidiphtheritic serum. If the control dies and the treated animal
survives, the proof of the identity of the organism isolated with the
Klebs-Loeffler bacillus becomes absolute.

7. Inoculate guinea-pigs subc