3800 PROGRESS OF MICROSCOPICAL SCIENCE. 
layer having wholly disappeared, and the red corpuscles being crowded 
together to the very edge of the vessel. Here, then, is another marked 
difference between the web and the muscle.” * 
Mr. Lewis’ Freezing Microtome.—The adjacent cut represents this 
instrument, which Mr. Bevan Lewis, F.R.M.S., has described at some 
length in the ‘Journal of Anatomy’ (vol. xi.), and which is not so 
novel as he seemed to think at first. In fact, he states at the conclu- 
sion of his paper that he then became aware of a previously described 
instrument by Mr. Hughes; but he says that in his (Mr. H.’s) micro- 
tome, the spray is not so directly brought to bear upon the tissue, 
which consequently requires from five to eight times as long a period 
to freeze, with, of course, a corresponding increase in the loss of ether : 
this is of material import when absolute anesthetic ether is em- 
ployed. He states that “the instrument consists of three portions: 
(1) an ordinary Stirling’s microtome; (2) a section plate; (3) a 
freezing and condensing chamber. The simplicity of the arrange- 
ment will, I trust, recommend its use amongst my fellow-workers in 
the department of cerebral histology. Reference to the accompanying 
woodcut will place the reader in possession of the plan upon which 
H 
this instrument has been constructed. The section plate (a) is riveted 
by a brass arm to the microtome (b). The freezing compartment (c) 
consists of a cylinder (d) and a condensing chamber (e), the latter 
being formed of brass with a sloping floor leading to the exit-tube, 
which is provided with a stop-cock (f). The cylinder is capped with 
tin-foil stretched across it, and has an orifice (d) through which the 
nozzle of the spray apparatus is introduced. In using this instru- 
ment it is only necessary to bring down the cap of the cylinder from 
one-fourth to three-eighths of an inch below the level surface of the 
section plate, and to place in it a section of brain of about the same 
thickness. The spray instrument is inserted at the orifice,and by the 
ordinary double elastic balls a free play of ether beneath the cap 
freezes the tissue in from twenty to thirty seconds or less. On with- 
drawing the spray instrument, the slight play of ether, still continuing 
from the remaining tension of the elastic ball, is utilized by being 
* “Proceedings of the Royal Society,’ No. 176. 
