346 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
by the following procedure. The sections are stained for twenty-four 
hours in an incubator in carbol-fuchsin, and then decolorised with Ebner’s 
fluid. After having been washed in 70 per cent, spirit, they are trans- 
ferred to acetic acid vesuvin solution (Kahlbaum) for some hours. Next 
they are washed in water and in 70 per cent, spirit, and are then stuck 
on a slide, after which they are stained by Weigert’s method. The 
anilin-xylol should be allowed to act for some time, otherwise the nuclei 
will be blue instead of brown. If the differentiation be successful, the 
nuclei are brown, the fibrin blue, the tubercle bacilli red, and other 
bacteria blue. 
(5) Mounting-, including- [Slides, Preservative Fluids, &c. 
To Prevent Freezing of Formol.* — Dr. A. Milani finds that the 
addition of 25-35 parts of glycerin to the formol solution prevents the 
danger of freezing. 
(6) Miscellaneous. , ; 
Eapid and Improved Method for Counting Plate Colonies.f— 
Dr. H. J. van’t Hoff has devised the following method for counting 
bacterial colonies on plates : — On the middle of a gelatin plate having 
a diameter of about 15 cm. is dropped about 0*2 ccm. of water. The 
water is then distributed over the surface of the gelatin by merely 
rolling the capsule about, care being taken to prevent the water from 
reaching the side. Distributed in this way, the colonies develop quite 
separately, and so rapidly that in two days it is possible to obtain a 
better quantitative result by this method than in five or six days by the 
ordinary procedure. 
Method for Examining Malarial Blood. f — Dr. N. Macleod uses 
strips of ordinary note-paper 0*5 in. wide and about 1J in. long for 
smearing cover-glasses with malarial blood. The straight edge is drawn 
its full half inch through a drop of blood not larger tjian a pin’s head, 
and then the edge drawn across the cover-glass. In this way a thin film 
which dries very rapidly may be spread on cover-glass or slide. The 
film must be mounted dry. With a 1/4-in. objective crescents and the 
larger pigmented parasites, and with a 1/12 oil immersion the smaller 
pigmented forms, can be easily seen. The method, however, cannot be 
relied on for the detection of unpigmented forms without very con- 
siderable experience, and should be supplemented by staining, or the 
examination of fresh undried films. 
Bacteriological Diagnosis of Leprosy.§ — The method advocated by 
Messrs. Johnston and Jamieson for the bacteriological diagnosis of 
leprosy is extremely simple, and consists in smearing a cover with a 
drop of serum obtained by scraping one of the leprosy nodules. This 
is stained with carbol-fuchsin, and decolorised with sulphuric acid and 
methylen-blue. The bacilli of leprosy are found in large numbers, 
and this fact alone is sufficient to distinguish leprosy from tubercle 
bacilli. Lepra bacilli also stain readily with simple anilin dyes, while 
tubercle bacilli do not. 
* Zool. Anzeig., xx. (1897) pp. 206-8. 
t Centralbl. Bakt. u. Par., l te Abt., xxi. (1897) pp. 731-3 (1 fig.). 
X Lancet, 1897, ii. pp. 85-6. 
§ Montreal Med. Journ., 1897. See Epit., Brit. Med. Journ., 1897, p. 92. 
