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MICROSCOPY. 121 
and distinct and the intervening spaces are said to be sufficiently 
translucent, which would suggest that the contrivance is best 
suited for the rapid and easy performance of easy work. 
Similarly a goniometer is made by reducing a graduated circle 
of eighteen inches to a transparent positive of suitable size to be 
placed in the draw-tube below a positive eye-piece. The eye-piece 
is furnished with a cob-web line, and its rotation is easily read off 
on the scale in its focus. This goniometer, which could be made 
for a few shillings, would seem to be a valuable accessory to all 
microscopes, especially to those not possessed of a graduated 
concentric stage. 
Tur Diarom Hoax.—Many readers have enjoyed, in a late 
medical journal, the ingenious essay on test-objects, in which the 
new immersion one-seventieth of 191°, wet with fluoric acid and 
illuminated by a new eccentric parallelopiped with fluorescent rays 
exclusively, is represented as revealing that the structure of Pleu- 
rosigma angulatum is like the Nicholson pavement ; and that a 
new diatom, fortunately rare, has beads, more than one hundred 
and forty-seven millions to the inch, which are invisible by all 
other lenses. and to all other observers. They will be further 
amused by learning from the “t Boston Journal of Chemistry ” that 
some foreign medical journals have seriously reviewed. this bur- 
lesque and discovered it to be a hoax. ; 
Tue Rep Broop-corruscLe.— Mr. E. Ray Lankester presents 
in the “Quarterly Journal of Microscopical Science” an interest- 
ing contribution to our knowledge of the physical structure of the 
red blood-corpuscle and the action of gases and vapors upon it. 
The red blood-corpuscle has no outer coat distinct from its con- 
tents and having a pronounced inner limitation, none being visible 
under the highest powers of the microscope (what might be mista- 
ken under low powers for such proving under high powers to be 
an illusion of refraction), and the corpuscles, torn or cut by draw- 
ing a needle across the slide, suffering no escape of viscid material 
from their interior, but furnishing portions which by the collapse 
of their edges assume a rounded form; yet their surface must be 
differentiated into a.film or pellicle having no definite inner boun- 
dary, and similar to the pellicle which forms on a cooling mass of 
Jelly, since they become wrinkled when subjected to oblique pres- 
sure and recover their form and outline again with great elasticity 
and precision. 
