526 The American Xaturalht. 



[.Jun,,. 



become the female portion. If both derivatives of the germinal 

 epithelium were to develop, both the first central, and the second, peri- 

 pheral, there would result an hermaphrodite gland. 



The epithelial cells that form the sperms in the male would be thus 

 somewhat older, ontogenetically, than the epithelial cells that form 

 the ova in the female. 



The Tail in the Human Embryo.— Dr. Franz Keibel 1 having 

 sectioned and reconstructed several human embryos of different ages 

 endeavors to decide the difficult question as to the value of the poster- 

 ior end of the trunk, as to the existence and magnitude of what may 

 be truly called the tail. 



In spite of the various criteria used by His in determining what is 

 to be regarded as the caudal region, such secondary changes as the 

 movements of the pelvis made known by Rosenberg make the problem 

 much more difficult than might at first appear. The author counting 

 back from the head reckons those mesoblastic somites or vertebra? as 

 caudal which would be posterior to the sacrum of the adult. 



From the present material and the observations of His and Fol it 

 seems that embryos of 4 to 6 mm. have a true projecting tail with 

 chorda, mesoblastic somites, medullary tube and also a caudal intes- 

 tines or post-anal gut. Later the number of caudal segments may be 

 as many as six while the intestinal, tube closes first at the base then 

 towards the tip of the tail. 



This caudal appendage is thus more perfectly developed in the 

 embryo than in the adult : a fact which the author would add to the 

 various facts of human and comparative anatomy, which he enumer- 

 ates as evidence of the former existence of a complete tail in the 



Embryonic Veins in the Limbs of Amniota.— Dr. F. Hoch- 

 stetter 2 finds in the limbs of the rabbit, chick and the lizard a 

 remarkable similarity in the earliest condition of the venous supply. 

 Moreover the anterior and the posterior limbs are at first identical in 

 this respect. 



In such an embryonic limb, before the digits are apparent, there is 

 an axial vessel serving as an artery and sending blood by radiating 

 branches towards the single vein, which borders the pad-like foot. 



