110 Comparative Neurology. [ February, 
binding it to the visceral plexuses lengthen and broaden out into 
such great fasciculi as the splanchnic and cardiac nerves. 
Second System Ganglia—By quantitative caudal development 
of the cerebral ganglia homologies of Invertebrata, as supra- 
cesophageal, optic, auditory, pedal, or tactile, commissurally con- 
nected by afferent fibers posteriorly (columns of Goll and Burdach), 
and by efferent fibers anteriorly (columns of Tirck and anterior 
fundamental tract), a view is obtained of the primitive spinal cord 
segments ununited. Spitzka records that the planes of junction 
of the original segments may be still made out by the poorness 
in cellular elements of such areas under microscopic examination, 
while the centers of the spinal ganglia are determinable by their 
richness in these elements. Longitudinal fusion and consequent 
shortening of this chain forms the central tubular gray of the 
spinal cord. 
The “ medullary white” of Flechsig first appears in the columns 
of Burdach, in the foetus of 25 cm. Spitzka says it also appears 
in the processus cerebello ad cerebrum. This is reasonable, for 
the processus cerebello ad cerebrum is a continuation of the col- 
umns of Goll and Burdach, as will appear later in this CESCHpiee 
The second system ganglia consist of: 
All the coalesced segments which form the spinal cord. 
The medulla oblongata gray. 
The gray masses in the pons Varolii. 
The optic thalami and soft commissure. 
The tuber cinereum. 
The (doubtful) olfactory ganglion of Luys. 
The caudate and lenticular nuclei of the corpora striata. 
The hypophisis cerebri being the atrophied end of the cord, 
needs no numerical consideration. 
Third System Ganglha.—Turning again to the Amphioxus, we 
find that the second system ganglia, or spinal cord, give off affer- 
ent and efferent nerves dorsally and ventrally, without interverte- 
bral ganglia, cerebellum, or anything resembling a cerebrum, The 
“second pair” of nerves of the head end, instead of passing ven- 
trally and dorsally, as do those of the lower segments, run back- 
ward or caudally; those which run from the tail to the head 
APY Vo 
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along the dorsum, are afferent, while those projected backward 
along the ventral portion of the body, are efferent. 
These sets of nerves resemble strikingly in many particulars, 
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