416 SUMMARY OF CURRENT RESEARCHES RELATING TO 
With these high powers he claims that it would be possible to state 
that corpuscles were not those of the sheep, goat, horse, cow, or ox, and 
probably the dog, or of any Mammal except the guinea-pig or opossum. 
Prof. Wormlev,'on the other hand, who has made determinations of 
the apparent size of red corpuscles under a magnification of 1150, came 
to the general conclusion “ that the Microscope may enable us to deter- 
mine with great certainty that a blood is not that of a certain animal, 
and is consistent with the blood of man ; but in no instance does it in 
itself enable us to say that the blood is really human, or indicate from 
what particular species of animal it was derived.” 
Prof. Formad’s methods of observation of blood-corjDUsdes are as 
follows : — 
A drop of blood is placed upon a slide and the edge of another slide 
is quickly drawn across so as to distribute the corpuscles as evenly as 
possible between them. 
Two micrometers, the one a stage-piece, the other an eye piece 
micrometer, are used. The stage micrometer, which consists of a glass 
slide ruled to a scale either in millimetres or fractions of an inch, serves 
to establish the correct value of the lines ruled upon the micrometer. 
The eye-piece micrometer is a slip of glass, with fine lines ruled to 
a uniform scale, which fits into the eye-piece of the Microscope. By 
the stage micrometer the number of divisions of the eye-piece micrometer 
required to fill one of the divisions of the stage micrometer is noted. 
Thus, if with a 1/12 Zeiss homogeneous-immersion lens the 1/100 in. 
division of the stage scale covers exactly twenty places in the eye- 
piece scale, then each division of the eye-piece micrometer will* be equal 
to the 1/20000 in. When the adjustment of the scale has been thus 
made the slide is brought into focus under the eye-piece micrometer 
and the number of divisions occupied by a blood-corpuscle is noted. 
The average of 100 measurements made in this way upon perfectly 
round biconcave corpuscles only is then taken. 
For photographic purposes the blood is mounted directly upon a 
glass stage micrometer, and both blood and micrometer appear sharply 
defined in the picture. The measurements are then made directly upon 
the negative. 
Bohm and Oppel’s Pocket-book of Microscopical Technique.* — 
This little manual has now got into its second edition, and it deserves 
some praise, as it is an excellent compendium of the myriad details 
necessary for the examination of animal tissues. The first section deals 
with the Microscope, its accessories and manipulation, and the second 
section with the preparation of the object. After this follows the special 
part in which the organs and tissues are separately treated of. 
It is certainly one of the most useful compilations we have seen, and 
it would no doubt command, if in an English dress, a considerable sale, 
for a little pocket-book on microscopical technique is a desideratum. 
The get-up of the work is very good. 
Mixtures of Antiseptics. f — M. J. de Christmas after alluding to the 
fact that several observers had laid it down that mixtures of several 
* ‘ Taschenbuch der Mikroskopischen Tecknik/ A. Bohm u. A. Oppel, 2nd ed., 
Munich, 1893, 192 pp. 
t Ann. Inst. Pasteur, 1892, p. 374. See Centralbl. f. Bakteriol. u. Parasitenk., 
xiii. (1893) pp. 107-8. 
