104 R. J. ANDERSON [AuGusT 
many words. Owen’s typical vertebra, it will be remembered, has 
growths above, below, and at the sides. The two dorsal growths end 
in the spine; the lateral growths are the transverse processes (dorso- 
lateral), and the lower growths (ventro-lateral) may join the ribs which 
form an arch like the dorsal one. The limbs are represented by 
diverging appendages. The limb folds seem to partake of the quadri- 
lateral symmetry type in some fishes. Humphry pointed out that the 
term “duality” is inapplicable to the nervous system and skeleton. 
The lineal axis of the embryo sends off the processes referred to, and there 
is therefore a quadrilateral rather than a bilateral symmetrical arrange- 
ment.’ Humphry, however, distinguished between the body as a whole 
in this regard and the separate parts. Leaving out the bodies of the 
vertebrae which are variously formed, but originally developed round 
an endodermic growth, one can make out a radiate symmetry of four, 
five, or six rays, according as certain processes are counted or omitted. 
The pillars of the dorsal arch may be counted separately, so may the 
transverse processes and body processes ; or, reckoning each pair as one 
process forming a two-pillared arch, there are four arches. The spinal 
nerve cord section occupies the dorsal arch, the sympathetic the ventral, 
and the posterior root ganglia are at the sides. It is clear, however, that 
the spinal cord may be looked upon as made up of two lateral halves, 
so may the sympathetic cords. A survey of the entire system tends 
to render the bilateral symmetry of each less clear, whether taken 
together or separately. The sympathetic seems to be of more con- 
siderable relative importance in early life, judging from the drawings of 
Paterson. The ganglia are often large in man, but the size appears to 
be due in the abdominal ganglia to fibrous tissue (D. J. Cunningham). 
W. Alexander has removed the superior cervical in man with advantage 
to the patient, proving how far the system has gone back.” The sympa- 
thetic is, however, of enormous interest because of its distribution, 
subsidized by the spinal, in the viscera and arterial coats. The symmetry 
that takes account of the spinal cord, divided into two equal lateral 
parts, has also reference to the division of the abdominal nervous system, 
so that a modified quadrilateral symmetry may appear as a bilateral 
symmetry. The dorsal and ventral systems, as every one knows, are 
mainly independent of one another. The presence of the serous mem- 
branes secures this independence in part, but the nerve connections do 
not favour a ready transference of impressions from one system to the 
other. The connections, however, come into use often in disease, and 
a slight activity in the terminals of either systems, may produce a 
profound disturbance in the district supphed by the other. The sym- 
pathetic ganglia associated with the cerebral system are obscured by the 
magnitude of the large brain and its connections in vertebrates. The 
1 See Quain’s ‘‘ Anatomy,”’ 8th ed. 
2 Nerve cells being now proved to be trophic only, the fibres collectively assume more 
prominence in our estimate of the value of a nerve tract, or district. 
