108 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
strument allowed only a backward and forward movement. The nature 
of the improvement is shown in fig. 23. 
(4) A shaping apparatus . — It is very convenient to possess an appa- 
ratus capable of cutting the paraffin blocks into true rectangular forms ; 
at the very least the opposite faces should be accurately parallel to the 
knife-blade. Fig. 24 shows this piece of auxiliary apparatus. The knife- 
holder slides in the swallow- tailed grooves of the vertical part of the 
cast-iron stand. Behind the runners of the knife-carrier is a vertical 
column space, which makes it possible to fix a square plug by means of 
a winged nut just visible on the right of the figure. As the knife-slide 
in sinking strikes on this plug, the extent of its fall can be accordingly 
regulated. 
The horizontal slide for the paraffin block moves in swallow-tailed 
grooves, and is regulated by a milled head as shown. The cylindrical 
metal piece on which the paraffin saucer is fastened is a hi oad rotatory 
clamp-ring divided into quadrants ; and this clamp-disc is rotatory on a 
second clamp-disc firmly secured to the slide ; the adjacent milled head 
fastens both discs together, whereby the paraffin saucer is made fast. 
When one side of the paraffin block has been shaped, the quadrant disc 
is released, rotated 90°, and again fixed ; thus a second side is shaped, 
and so on. For shaping the block an ordinary razor is used, but too 
broad a one should not be chosen, as a feather-edged blade breaks the 
block. It is best to incline the knife about 5° to the vertical. For this 
purpose a copper right-angled triangular plate is added to control the 
fixing of the knife. 
(4) Staining 1 and Injecting. 
Staining the Capsules of Pneumococcus and of the Bacillus of 
Friedlaender.* — Mr. A. MacConkey recommends the following solution 
for staining bacterial capsules ; the combination gives a clear image 
which photographs well. Dahlia 0*5 grm. ; methyl-green (00 crystal) 
1*5 grm.; saturated alcoholic solution of fuchsin 10 ccm. ; distilled 
water to 200 ccm. The dahlia and methyl-green are rubbed up in a 
mortar with part of the water until dissolved, then the fuchsin is added, 
and finally the rest of the water. 
Staining . — Prepare the film in the usual way. Flood the cover-slip 
with the stain, and hold over the flame until steam begins to arise. 
Then place aside for about five minutes, wash in water, dry, and mount 
in balsam. If the film be treated with acetic acid before staining, the 
result is not so good. 
The solution is also a good general stain, especially for the Klebs- 
Loeffler bacillus and for Bac. tijyhosus and Bac. coli communis. 
Permanent Stain for Starch.f — A very good and durable stain for 
starch may be obtained, says Mr. J. H. Schalfner, by the use of anilin- 
safranin and gentian-violet. (1) Anilin-safranin solution is prepared 
by mixing equal parts of anilin water and saturated alcoholic solution 
of safranin. (2) Two per cent, aqueous solution of gentian- violet. 
Stain for 2-4 hours in the safranin, and from 2-8 minutes in the 
gentian-violet. The slides should be taken through the alcohols 
quickly. The stain is a purplish-red, and the cells look filled with 
the coloured starch-grains. 
* Lancet, 1898, ii. p. 1262. f Journ. Applied Microscopy, i. (1898) p. 181. 
