394 Dr Martin Barry on Fibre. 
for a single ring ; and they consequently form a coil. At the outer part 
of this coil, the filament, already stated to be flat, often presents its edge ; 
whence there arises a greater thickness of. the corpuscle, and an appear- 
ance of being cut off abruptly at this part ; while in the centre there is 
generally found the unappropriated portion of a nucleus ; and hence the 
central eminence, surrounded by a depression, in those corpuscles which, 
from the above-mentioned cause, have the edge thickened. The nucleus 
of the blood-corpuscle in some instances resembles a ball of twine ; being 
actually composed, at its outer part, of a coiled filament. Insuch of the 
invertebrata as the author has examined, the blood-corpuscle is likewise 
seen passing into a coil. 
The filament, thus formed within the blood-corpuscle, has a remark- 
able structure; for it is not only flat, but deeply grooved on both sur- 
faces, and consequently thinner in the middle than at the edges, which 
are rounded ; so that the filament, when seen edgewise, appears at first 
sight to consist of segments. The line separating the apparent segments 
from one another is, however, not directly transverse, but oblique. 
Portions of the clot in blood sometimes consist of filaments having a 
structure identical with that of the filament formed within the blood-cor~ 
pusele. The ring formed in the blood-corpuscle of Man, and the coil 
formed in that of Birds and Reptiles, have been seen by the author un- 
winding themselves into the straight and often parallel filaments of the 
clot ; changes which may be also seen occurring in blood placed under 
the microscope before its coagulation ; and similar coils may be perceived 
scattered over the field of view, the coils here also appearing to be altered 
blood-corpuscles, in the act of unwinding themselves ; filaments, having 
the same structure as the foregoing, are to be met with apparently in 
every tissue of the body. The author enumerates a great variety of or- 
gans in which he has observed the same kind of filaments. 
Among vegetable structures, he subjected to microscopic examination 
the root, stem, leaf-stalk, and leaf, besides the several parts of the flower: 
and in no instance of phanerogamous plants, where a fibrous tissue exists, 
did he fail to find filaments of the same kind. On subsequently examin- 
ing portions indiscriminately taken from ferns, mosses, fungi, lichens, and 
several of the marine alge, he met with an equally general distribution 
of the same kind of filaments. The flat filament seen by the author in 
all these structures, of both animals and plants, he states to be that usu- 
ally denominated a fibre. Its appearance is precisely such as that of the 
filament formed within the corpuscle of the blood. It is known, he re- 
marks, that discoid corpuscles circulate in plants; and it remains to be 
seen whether or not filaments are formed also in these. 
By gradually tracing the fibre or filament above mentioned into similar 
objects of larger size, the author endeavours to shew that it is not pos- 
sible to draw a line of separation between the minutest filament, and an 
object being, to all appearance, composed of two spirals running in oppo- 
site directions, and interlacing at certain regular intervals ; an arrange= 
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