Bauhaus-Universität Weimar

THE ORGANIC AND ANIMAL SYSTEMS OF MUSCLES. 641 
motion are developed in the external layer; those endowed with organic 
or involuntary motion in the internal layer; and in the middle or vas¬ 
cular layer is formed the heart, together with all the parts belonging to 
the vascular system, which, at a later period, ramify in the structures 
developed in the external* and internal laminae. The portion of the 
body formed in the external layer of the germinal membrane separates 
into the different structures of the animal nervous system, the osseous 
system, the system of voluntary muscles, and the skin. The portion of 
the body developed from the mucous layer separates into the different 
structures of organic life, namely, the fibrous structures forming the sup¬ 
port of the different organs, such as the fibrous tunic of the intestinal 
tube, (the tunica nervea of the older anatomists,) the serous membranes, 
the mucous membranes, the muscular coat lying between the fibrous 
and the serous, and, lastly, the organic nervous system. (Von Baer, 
Entiuickelungs-geschichte. Scholien.) This organic portion of the body 
includes the intestinal tube, the urinary and the generative apparatus, 
all of which have in nearly their whole extent an organic muscular 
layer, which is the sole cause of all the motions they exhibit. The 
proper pharyngeal muscles and the perinæal muscles, which are en¬ 
dowed with voluntary motion, and belong to the animal portion of the 
body developed in the external lamina, are not here included. Even 
the efferent ducts of the accessory glands of the organic system have a 
muscular coat continued on them from the muscular layer of the great 
tubes; for, though the muscular coat of these ducts has not, it is true, 
from their delicacy, been demonstrated so plainly as the other mem¬ 
branes, yet its presence is certain: the ductus communis choledochus, 
the ureters, and the vasa deferentia have been seen to contract, both 
spontaneously and under the application of stimuli. That the efferent 
ducts and their glands are originally developed from the walls of the 
tubes into which they open is an ascertained fact, at least, with regard 
to the glandular apparatus of the intestinal tube. 
The muscles of animal life are distinguished from the pale muscular 
coats of the organs of the organic portion of the body, which are not 
subject to volition, not merely by their moving under the influence of 
volition, by their red colour, and their solidity, but even by the great 
difference of their microscopic character. We see that the primitive 
muscular fasciculi of the animal system present, under the microscope, 
transverse markings, and that the primitive fibres of these muscles have 
regular varicose enlargements following each other in close succession; 
while the fasciculi,of the muscular coats of the intestines, urinary blad¬ 
der, and uterus are destitute of those cross markings, and their primitive 
fibrils uniform, not varicose, threads. In the oesophagus the two sys¬ 
tems border closely on each other; the muscles of the pharynx belong 
to the animal system, those of the oesophagus to the organic; but the 
first fourth of the proper oesophagus receives an investment from a 
stratum of muscular fasciculi, descending on it in an arched form to a 
defined limit, in which Schwann has discovered the transverse mark¬ 
ings and the fibrils of varicose structure; these, however, belong to the 
pharyngeal muscular apparatus: no such fasciculi are met with on the 
rest of the oesophagus. But according to M. Ficinus (De Fibræ Mus- 
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