242 MICROSCOPY. 
ground illumination with medium powers, was introduced by Col. 
Horsley of the East Kent Natural History Society. He uses light 
reflected from the inside of a broad, short, silver-plated tube 
beneath the object. The tube may be silvered, not very perma- 
nently, by rubbing it with a solution of nitrate of silver and hypo- 
sulphite of soda. Such a tube, placed in the stage opening, would 
give a more oblique illumination than could easily be obtai 
otherwise in instruments having a thick stage. 
' GLYCERINE IN Microscopy.— Dr. W. M. Ord, of St. Thomas 
Hospital, London, questions the safety of glycerine as a medium 
for studying and mounting microscopic objects. Its solvent 
power over carbonate of lime is well known, and he had found it 
ruinous to crystals of murexide, oxalate of lime, and triple phos- 
phate. Might it not produce unsuspected molecular changes 
in other objects? Portions of tissue preserved unaltered in : 
for years, might have been affected’ in molecular constitution by it 
at the first penetration and before the first observation. More 
light is wanted on this subject. 
Practica Histoocy.— Dr. Wm. Rutherford gives, in te 
Quarterly Journal of Microscopical Science for January 1872, A 
synopsis of his course of instruction in Histology. The paper's : 
too long to reprint and too dense for abstract, but it is full of 
suggestions that will be useful to many others besides me 
students. The author has a dashing and not unattractive manne? 
of expressing his dissent from the opinions of most microscop 
in England and this country in regard to apparatus, ete. ; 
— Manasse 
e result of 
and se 
various 
a 
of the 
such 3 
. 
VARIATIONS IN Size or Rep BLOOD-CORPUSCLES. 
(“ Centralblatt” No. 44, October 28th, 1871) gives th 
more than forty thousand measurements on one hundred 
enty-four different animals, intended to show the effect of 
physiological and morbid influences on the size of the red 
cles. In general, influences which raise the temperature 
body were found to diminish the size of the corpuscles 
very high temperature of the external medium, or septic p° a 
Excess of carbonic acid in the air also acts in the Se 
Oxygen, on the other hand, increases the dimensions © 
corpuscles, and so do, in general, all substances which dept e 
animal temperature, as external cold, quinine, hydrocy aor : 
and intoxicating doses of alcohol. Morphia is an exception, 
