Royal Society. 133 
mis.” By Erasmus Wilson, Esq., F’.R.S., Lecturer on Anatomy and 
Physiology in the Middlesex Hospital. 
The author adduces evidence derived from his microscopic obser- 
vations, in confirmation of the commonly received doctrine respect- 
ing the origin of the cells of the epidermis and epithelium generally, 
from the materials furnished by the liquor sanguinis or plasma of 
the blood; which fluid, passing by endosmosis through the walls of 
the capillary vessels and peripheral boundary of the surface, deve- 
lopes granules by a vital process, analogous to coagulation. Ona 
careful examination of the inner surface of the epidermis with the 
aid of the microscope, he finds it to be composed of four kinds of 
elements, arranged in such a manner as to constitute an irregular 
plane, similar to a tesselated or mosaic pavement. These elements 
are,—l1. Granules, which the author terms primitive, of a globular 
form, solid and apparently homogeneous, and measuring about 
1-20,000th part of an inch in diameter. 2. Aggregated granules, 
having about double the diameter of the former and apparently com- 
posed of as many of these as can be aggregated together without 
leaving an unoccupied space in the centre of the mass. 3. Nucleated 
granules measuring in diameter from the 6000th to the 4000th part 
of an inch, each being composed of an aggregated granule as a 
nucleus, enveloped by a single layer of aggregated granules, giving 
to the whole mass an oval or circular, and at the same time flat- 
tened shape. Their constituent granules have acquired, during this 
aggregation, greater density, and are separated from each other by 
distinct interstitial spaces filled with a transparent homogeneous sub- 
stance. 4. Nucleolo-nucleolated cells pervading the deep stratum of 
the epidermis, and of which the longer diameter measures from the 
3000th to the 2500th part of an inch. These cells, which constitute 
the principal portion, and may be regarded as the chief constituent 
of the epidermis, are formed from the nucleolated granules, on the ex- 
terior of which there is superposed a transparent layer, bounded by a 
well-defined outline, by the dark interstitial substance of the wall of the 
cell; the nucleolated granule being the nucleus, and the aggregated 
granule the nucleolus of these primitive cells of the epidermis. The 
author is of opinion that the nuclei, up to a certain point, grow with 
the cells, by the separation of the original granules from the deposi- 
tion between them of interstitial matter, and also by the cleavage of 
the latter and the consequent multiplication of the granules. This 
peripheral growth of the cells is totally different from the mode of 
growth described by Schwann, and explains the disappearance of the 
nucleus in the scales of the epidermis. The observations of the 
author lead him to believe that the same process of development and 
of growth is followed in the epithelium as in the epidermis; and he 
offers evidence, showing that similar arrangements take place in the 
cells of melanosis, in the pigment cells of ‘the choroid membrane of 
the eye, and in those of the skin of the negro. 
“On the Temperature of Man.” By John Davy, M.D., F.R.S 
Lo & E. 
Having in a former paper shown that, contrary to a commonly 
