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X, On the Development of Striated Muscular Fibre in Mammalia. By William 
§. Savory, Tutor and Demonstrator of Anatomy of St. Bartholomew' s Hospital 
Medical College. Presented hy James Paget, F.R.S. 
Received December 9, 1854, — Read December 21, 1854, and January 11, 1855. 
XhE descriptions which have been hitherto given of the development of muscular 
fibre may be included in a few words. Little or nothing of importance has been 
discovered beyond the original researches of Valentin and Schwann, Concerning 
these Schwann says, “ In order briefly to recapitulate our researches into the gene- 
ration of muscle, the process may be thus stated. Round cells, furnished with a 
flat nucleus, are first present, the primary cells of muscle. These arrange themselves 
close together in a linear series ; the cells thus arranged in rows coalesce with one 
another at their points of contact ; the septa by which the different cell-cavities are 
separated then become absorbed, and thus a hollow cylinder closed at its extremities, 
the secondary cell of muscle, is formed, within which the nuclei of the original cells, 
from which the secondary cell has been formed, are contained, generally lying near 
together on its wall. This secondary cell then passes through all the stages of a 
simple one. It expands throughout its entire length, whereby the nuclei are further 
removed from one another, and sometimes even become elongated in the same 
direction. A deposit of a peculiar substance, the proper muscular substance, takes 
place at the same time upon the inner surface of the cylinder, by which the cavity is 
at first narrowed and at length completely filled. The cell-nuclei lie external to this 
substance, between it and the cell-membrane of the secondary cell. 
“The transverse strise in the voluntary muscles become more manifest, and the 
deposited substance is more distinctly seen to be composed of longitudinal fibres, as 
the foetus advances in age. The nuclei are gradually absorbed. The cell-membrane 
of the secondary muscle-cell remains persistent throughout life, so that each primi- 
tive muscular fasciculus is always to be regarded as a cell*.” 
This account has been generally accepted by those who have since written on the 
subject. Dr. Martin Barry, however, must be excepted. He entertains a very dif- 
ferent view of the origin of muscular fibre, and declares that the cells, by the coa- 
lescence of which the tubes are at first formed, are really blood-cells. He says that 
the blood-corpuscles apply themselves to one another in a linear series. By degrees 
* Microscopical Researches into the Accordance in the Structure and Growth of Animals and Plants, 
translated from the German of Dr. Th. Schwann, by H. Smith, 1847, p. 141. 
MDCCCLV. 2 L 
