10 



GEORGE L. STREETER 



lu'jiic Collection, No. 140()-3{)). Th(> growth of the cistern here 

 lias kepi jiaee with the increase in size of the labyrinth and 

 maintains the same general relations as regards the stapes and 

 the parts of the membranous labyrinth. The view of the cis- 

 tern in figure 6 is an oblique one which would tend to mislead 

 one as to its width. In reality it is relatively a little wider. 



SACCUS ENDOL. 



SCALA VESTIB.. 



Fig. 6 Lateral view of reconstruction of the left membranous laljyrinth 

 and the periotic spaces in a human fetus 85 mm. CR length (Carnegie Collection, 

 No. 1400-30) enlarged 9 diameters. Although the greater part of the cistern 

 abuts against the stapes it will be noted that it also is beginning to spread over 

 the dorsal surface of the utricle and along the inner border of the lateral canal. 

 The scala vestibuli communicates freely with the cistern and extends downward 

 along the apical surface of the cochlear duct throughout nearly two turns, show- 

 ing the characteristic sacculated appearance near its tip where the coalescence 

 of the spaces is less complete. 



Fig. 7 Median view of same model shown in figure 6. The oval indentation 

 in the proximal end of the scala tympani corresponds to the fenestra cochleae. 

 This space extends along the cochlear duct about the same distance as the scala 

 vestibuli; the two however do not communicate with each other as yet. The 

 peripheral border of the scala tympani is characterized by sacculations cor- 

 responding to spaces that are coalescing with the main space. This indicates 

 the direction of the growth of the scala at this time. 



