28 THE STRUCTURE OF MAN 
the assumption of the former presence of “ proto-vertebre ” 
[or mesoblastic somites] in this region, and these, in turn, might 
indicate the prolongation of the spinal 
cord into the caudal region in earlier 
embryonic stages (cf. Fig. 20). 
We must not, however, assume, as 
Gerlach justly observes, that a true 
tail, supported by skeletal tissues, 
would have developed in this embryo 
had it hved longer; because the 
tissues lying in the region of the 
caudal filament showed no traces of 
conversion into permanent cartila- 
einous or osseous vertebre. It was 
further observed, that at the point of 
junction between the posterior coccy- 
geal vertebra and the proximal end 
of the caudal filament, the chorda dor- 
salis had already disappeared. These 
facts indicate an attempt to return 
to the normal. The tail showed every 
sign of degeneration; but this does not detract from the great 
morphological interest of the case, which has led me to describe 
it at some length. . 
Three other certified cases of tail formation in human beings 
may be cited. 
The first is that of an Esthonian recruit, described by Max 
Braun in vol. iv. of the Zoologischer Anzeiger. The coceyx, in 
this case, did not recede into the groove of the buttocks under 
cover of the nates, but ended in an eminence, which, though not 
long, could be laid hold of and felt by the fingers. Thus exa- 
mined, it was found to lie in a direct line with the vertebral 
column and to contain distinct vertebrae, the last of which was 
about the size of a pea. It could not be certainly ascertained 
in the living subject whether this tail was due to numerical 
increase in the number of vertebre, or simply to a retention of 
the embryonic straight condition of the coccyx itself. It is a 
noteworthy fact, however, that Ecker’s glabella and foveola 
coccygea, or sacral dimple, had persisted. 
The second case is that of a newly-born female child, recorded 
by Lissner in 1872. Here also hard, irregular bodies, somewhat 
like the phalanges of a finger, could be distinctly felt in direct 
Fic. 18.—TAILED HUMAN EMBRYO. 
(After Gerlach. ) 
