70 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
English work, and is yet not complete. It is the purpose of Prof. Duval 
to publish a further portion so that the combined work shall he what 
would appear to us to be much more than a Handbook on Histology 
and <c Microscopic Anatomy.” The whole will represent a course of 
lectures given by him as Professor of the Faculty of Medicine of Paris, 
and they represent a deep and exhaustive knowledge of the subject. 
Our object is not to compare the two books that are here briefly con- 
sidered, but to those who desire to see the difference of treatment which 
like subjects receive, we would call attention to chapters iii., iv. and v. 
“ La cellule en general,” including “ Morpliologie et constitution de la 
cellule ” and “ Production des cellules,” and “ Les divers types de 
cellules” with chapter iii. in Mr. Clarkson’s book, and no better evi- 
dence of the character and the distinctive qualities of each treatise could 
be presented. Prof. Duval’s Precis (especially when its second part 
shall have appeared) might well be read after Mr. Clarkson’s treatise 
had been worked through from cover to cover ; and this is further seen 
in the really admirable chapters on “Le systeme nerveux,” the subtleties 
and refinements of which it would be impossible to epitomise, but to 
which — as indeed to the whole volume — we would advise those who 
desire a thorough, practical, and well-digested knowledge of the subject 
to go. 
a. Instruments, Accessories, &c.* 
(2) Eye-pieces and Objectives. 
New Objective by Queen & Co.j — Dr. A. C. Stokes gives the result 
of his examination of one of the new 1/12 objectives made by Queen 
& Co. The lens is a homogeneous-immersion, non-adjustable, and with 
N. A. 1*35. 
With oblique illumination from the achromatic condenser it resolves 
Surirella in styrax into black dots. With central light, under rather 
less than a one-third illuminating cone, Isthmia nervosa exhibits its 
secondary structure with good resolution of the postage-stamp fracture. 
The lens has a remarkably flat field and ample working distance, as it is 
intended as “ a rapid working lens for the practising physician.” 
(4) Photomicrography. 
Use of Colour-Screens for Photomicrography.^; — Prof. G. B. Todd 
has recently been using with considerable success screens made of 
coloured gelatin. Three reproductions of photographs of a transverse 
section of the rhizome of the common bracken are given, the first show- 
ing a photograph taken without a screen, the second taken with an 
orange screen, and the third with a red screen. The last gave by far the 
best result, the orange screen being intermediate between the first and 
third. The screens were made by laying a thin film of coloured gelatin 
over the aperture of the stage, fixing the slide with the object imme- 
diately above it, and then focusing and photographing. 
* This subdivision contains (1) Stands ; (2) Eye-pieces and Objectives ; (3) Illu- 
minating and other Apparatus; (4) Photomicrography; (5) Microscopical Optics 
and Manipulation ; (6) Miscellaneous. f Micr. Bull., xiii. (1896) p. 40. 
X Journ. Anat. and Physiol. Norm. Path. Human and Comp., xxxi. (1896) 
pp. 114-5 (3 figs.). 
