798 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
apparatus, which does not permit of the whole contents of the culture- 
tube being actually counted, since colonies are never so uniformly 
distributed that the counting of them in a given area or areas can give 
more than a rough approximation of the number actually present, has 
invented a new apparatus. It consists of a glass tube, 15 cm. long, the 
surface of which is divided by finely etched lines into square cms. 
The bore of this tube is such that the roll-culture-tubes just slide 
without play in it. Indiarubber rings keep the culture-tubes in 
position during the process of counting. A sheet of optical black glass 
forms a suitable blackground. 
The contents of each longitudinal row of squares are counted 
seriatim, the counting-tube being rotated by means of a milled collar. 
The number of colonies in each square is noted on a paper scheme 
having squares corresponding to those on the counter. It is only 
necessary to add together the contents of all the squares to obtain the 
total. 
In practice it has been found better to count the number of colonies 
in the space between the adjacent lines for the whole circumference of 
the tube — rotating the tube as the counting is done. 
Diagnosis of Cholera Bacilli by Means of Agar Plates.* — The 
recommendation of Koch induced Dr. Schiller to try agar plates for 
cultivating and examining cholera bacilli. The liquefied agar was 
cooled down as far as possible, inoculated, and plates made. After six 
hours in the incubator the condensation-water was found to have 
evaporated. The superficial and deep-lying colonies were found to 
be well separated. The former consisted of badly formed and badly 
staining bacilli, while the latter made good preparations. By allowing 
the surface to dry the superficial growth was stopped, and only the deep- 
lying colonies were made use of. With a little practice these could be 
easily recognized, though Finkler-Prior, Metschnikoff, and typhoid have 
some resemblance. These deep colonies are easily removed with a thin 
platinum needle. This needle was made by heating a platinum wire 
0 • 2 mm. thick in a Bunsen’s burner, and carefully drawing it out until 
it broke. When examined, comma-forms, spirilla, and S-forms are seen 
dancing about like a swarm of gnats ; this is sufficient to exclude typhoid, 
while on the other hand Finkler-Prior, that bugbear of the tyro bacterio- 
logist, and Metschnikoff would hardly be found in a cultivation made 
directly from faeces. 
With a fine platinum needle the whole colony can be easily re- 
moved and used for further examination. The cultivations were also 
characterized by staining well and showing well comma- and S-forms 
and spirilla. Even old colonies showing atypical growth returned to 
typical growth. 
Use of Formalin for Preserving Cultivations of Bacteria, f — 
According to Dr. G. Hauser the vapour of formalin possesses dis- 
infecting power sufficient to quickly inhibit the development of, and 
kill deep-lying colonies in plate cultivations. Plate cultivations can, 
* Deutsche Mediz. Wochenschr., 1893, No. 27. See Centralbl. f. Bakteriol. u. 
Parasitenk., xiv. (1893) pp. 292-3. 
t Munchener Med. Wochenschr., 1893, No. 30. See Centralbl, f. Bakteriol. u. 
Parasitenk., xiv. (1893) pp. 290-1. 
