IOIO $ General Notes. [October, 
vertebral column situated behind the trunk, it would be necessary 
o bear in mind that from the age of three weeks and up to that 
of two months and onwards, the human embryo is fortified with 
this organ, because at this epoch the coccygeal vertebræ occupy 
the axis of a very distinct cylindrico-conical appendage, and 
which arises from the posterior extremity of the trunk. If, with 
M. His, we take for our guide the position of the anus, the tail 
will be shorter, but it will not cease to be very apparent, espe- 
cially at the age of five or six weeks. 
However, it is admitted as absolutely demonstrated, that this 
caudal appendage of the human embryo never contains any other 
vertebræ than those which are found in the coccyx of the adult. 
Ecker, who has given, with conviction, the name of tail to the 
posterior extremity of the human embryo, has declared that he has 
never met with supernumerary vertebrz. This authcr has him- 
self studied the tail, very well formed, of a human embryo of 
9™™ in length, and he describes and figures all the terminal part 
as constituted of an unformed blastema. M. His found there, 
however, a prolongation of the dorsal cord and spinal marrow, 
but no segmentation. Both admit that beyond the thirty-third 
or thirty-fourth vertebra there is no other portion of the skele- 
ton. On this capital point my researches have led me to a result 
diametrically opposed to that of my predecessors. The errors of 
M. His arose from the fact that the embryos, the more advanced 
of which he made the reconstruction, those of 7™ and a fraction, 
have precisely thirty-four myomeres, viz., thirty-three vertebra, 
and he admits, without any other proof, that he was wordog over 
a definite stage. 
I have had the honor of presenting to the eae a résumé 
of my anatomical study of a human embryo of 5,8," viz., one 
twenty-five days old. This embryo had no more > than thirty- 
three somites, representing thirty-two vertebre. There is then 
an increase of the number during the fourth week. This fact led 
me to seek whether this number might not increase still more 
during the fifth week, and my attempt did not fail! The human. 
embryo of 9™™ to ro™ the age when the tail reaches its maxi- 
tie adil possesses a number of vertebre greater than that of 
the 
ALY m each other, since all three give the same result, 
n embryo of 8 to 9™™ has thirty-eight vertebræ. 
