40 H. LISSER 



NERVES— (A>s. 4, 5, 6) 



The 11. laryngeus superior (fig. 4) and inferior (fig. 6) can be fol- 

 lowed perfectly in these sections, from the point where they leave 

 the vagus, to their ultimate endings in the various muscles. No 

 reconstruction was made to prove positively an anastomosis 

 between the two, although a study of the sections suggested this 

 strongly. The innervations of the various muscle masses were 

 definitely seen. 



Embryo 144- — ^4 ^^- Sagittal sections — 50 fx 



Both the embryo under consideration and the following one of 

 16 mm. were cut sagittally and this circumstance affords excellent 

 opportunity for comparison. But the conclusion forced upon one 

 is, that there is very little disparity between the two, — practically 

 no changes of sufficient significance to warrant recording. This, 

 of course, may be due to the fact that the shorter embryo, may be 

 older than its length would indicate, or vice versa, as regards the 

 longer embryo. Yet it is not unlikely that little progress is made 

 in the various lar3^ngeal structures during this period of develop- 

 ment. There is an indication of beginning chondrification in the 

 16 mm. embryo, whereas there is none whatsoever in the 14 mm. 

 embryo, but otherwise the differences are negligible. A few draw- 

 ings were included of some sections (figs. 7, 8, 9), in the 14 mm. 

 embryo, which happen to show the musculature a little more 

 distinctly than in the 15 mm. sections — and they will also serve 

 the purpose of visualizing the similarity mentioned above. Ac- 

 cordingly, a detailed description of the larynx in this embryo will 

 be omitted, as the description of the 16 mm. one will suffice. 

 And moreover, more complete studies, such as graphic reconstruc- 

 tions, were made on the older embryo. 



Embryo 43-16 mm. Sagittal sections 



Embryo 43 measures 16 mm. V.B. and 4 mm. N.B. about 

 six weeks old. 



