VASCULAR DRAINAGE OF ENDOLYMPHATIC SAC 



69 



ology of the Carnegie Institution of Washington. The speci- 

 mens in most cases had been injected with India ink through the 

 umbilical vein and had been prepared in serial sections. In 

 some cases after injection and fixation they were dissected so 

 as to make total preparations which were rendered transparent 

 in wintergreen oil and were examined under the binocular micro- 

 scope. For purpose of topographical determinations, profile re- 

 constructions were made of several of the embryos that had been 

 cut serially and in some instances the structures were modelled 

 after the Born wax-plate method. These will be specified under 

 their separate descriptions. Although other embryos were ex- 

 amined the following list includes those that were chosen as best 

 representing the stages of growth of the endolymphatic sac and 

 its blood-vessels. 



HISTORICAL 



In the opinion of the earlier embryologists the endolymphatic 

 appendage represents the last portion of the ear vesicle that is 

 attached to the skin, and which becomes drawn out into a stalk- 

 like elongation as the vesicle recedes from the surface. They 

 further pointed out that it corresponds to the narrow tube found 

 in Selachians that passes dorsall}^ through the cartilagenous skull 

 to reach the surface of the head where it opens and thereb}^ con- 

 stitutes a canal that leads from the outside directly to the laby- 



