608 
DR. MARTIN BARRY ON THE CORPUSCLES OF THE BLOOD. 
be distinguished, either in colour, form, or general appearance. (The epithelium- 
cells in question are frequently observed to lie in the same direction, their long axes 
being parallel.) 
50. But if the great mass of the soft parts, muscle, is formed of corpuscles of the 
blood, how many tissues are there which they may not form?-|~ 
51. We are indebted to Schwann for the very important discovery, that “ for all 
the elementary parts of organisms there is a common principle of development the 
elementary parts of tissues having, as he has shown, alike origin in cells, however dif- 
ferent the functions of those tissues. The facts made known in the present memoir, 
if established by future observation, will not only afford proofs of the justness of the 
views of Schwann, but they will farther show that objects having all the same colour, 
form, and general appearance, namely, the corpuscles of the blood, enter immediately 
into the formation of tissues which physiologically are extremely different. We have 
seen some of these corpuscles to arrange themselves into muscular fibre, and others 
to become metamorphosed into constituent parts of the chorion. It is not, however, 
more difficult to conceive objects so much alike undergoing transformations for pur- 
poses so different, than it is to admit a fact made known by two of my preceding 
memoirs^ ; namely, that the nucleus of a cell having a central situation in the group 
which constitutes the germ, is developed into the whole embryo, while the nuclei of 
cells occupying less central situations in the group, form no more than a minute por- 
tion of a membrane §. It is known that in the bee-hive, a grub is taken for a special 
purpose, from among those born as workers, which it perfectly resembles until nou- 
rished with peculiar food, when its development takes a different course from that of 
every other individual in the hive. 
f “ The nerves,” says Schwann, “ appear to arise in the same manner as the muscles ; namely, through 
coalescence of primary cells in contact with one another and in a line, by which there is formed a secondary 
cell. But the primary nerve-cells have not been with certainty observed, because — so long as they are primary 
cells — they are not to be distinguished from the neutral cells, out of which arises the whole organ. ***The fibres 
[secondary cells] are pale, granulated, and***hollow. There now takes place, as in muscles, a secondary de- 
posit upon the inner surface of the fibre-w r all, that is, upon the inner surface of the membrane of the secondary 
nerve-cell. ***On the appearance of this deposit the cell-nuclei are usually absorbed; yet single ones continue, 
and then lie externally between the [deposited] substance and the [secondary] cell-membrane, ***as in muscles. 
The remaining cavity of the secondary cell appears to be occupied by a tolerably firm substance, the band dis- 
covered by Remak.” (Schwann in R. Wagner’s Lehrbuch der Physiologie, I. pp. 141, 142.) Should it be 
found that nerves too are formed of blood-corpuscles, this band of Remak may perhaps be constituted by coa- 
lesced objects similar to those apparently uniting to form the central substance in the muscle-cylinder (par. 38.), 
and which appear to be the essential part of altered corpuscles of the blood. — “The external appearance of 
tendons in the embryo,” says Valentin, “ is reddish, and notunlike the pale muscle-structures.” (Entwickel- 
ungsgeschichte, p. 270.) 
I Researches in Embryology, Second and Third Series, l. c. 
§ Which I provisionally called the amnion. 
