On the Human Tail. 
1 885.J 
417 
this is the faCt, and that the tail vanishes from the animal 
series before we reach that mythological “great gulf” which 
is supposed to separate beast from man. Yet they are not 
satisfied, and still persist, as in particular does the author of 
a work recently noticed in the “Journal of Science,” in en- 
tangling themselves with this appendage. 
Hence it may be useful if we lay before our readers some 
researches which M. H. Fol has recently submitted to the 
French Academy of Sciences. He asks, does the human 
embryo ever present at the posterior extremity of its body 
anything which merits the name of tail ? This question 
must give rise to a discussion which cannot fail to be lively, 
unless we have previously made the necessary distinctions 
and have come to an understsnding on the strict definition 
of the terms employed. 
It is necessary at the outset to distinguish teratological 
cases from the far more important phenomena of normal 
em'bryogeny which are about to engage our attention. Then 
we must agree as to the meaning of the word tail. Is this 
term applicable to every conical or cylindro-conical appen- 
dage at the posterior extremity of the back, whatever may 
be the tissues of which it is composed ? Or should it be re- 
served for an organ containing a prolongation of the verte- 
bral column ? This latter definition seems to preponderate. 
An appendage devoid of vertebrae is not a true tail in the 
anatomical sense of the term, but merely a simple caudal 
prolongation. 
In the monstrosities described by L. Gerlach, Bartels 
and Ornstein, the appendage, whether filiform or voluminous,' 
did not contain any evident undeniable vertebrae, and the 
total number of these bony structures did not exceed the 
regular number of a normal man. 
As regards young embryos, an understanding is not pos- 
sible if we do not first determine the point where the caudal 
vertebrae begin. Shall we fix the limit at the point where 
the tail branches off from the body ? Or are we to be guided 
by the position of the anus ? Or must we give the name 
caudal to all the vertebrae situate behind the sacrum ? This 
last-mentioned view has prevailed in comparative anatomy, 
and from this point of view we may say that the adult man 
possesses a tail, since he presents four or five coccygian ver- 
tebrae, situate beyond the sacrum. The minimum, in this 
respeCt, is reached by the chimpanzee, which has only two 
or three coccygian vertebrae. This ape is consequently, 
when mature, further from possessing an externally visible 
tail than is the normal adult man — a faCt not without 
significance. 
