158 GEORGE L. STREETER 



the acoustic root fibers, however, can be seen entering the side 

 wall of the brain near the endolymphatic duct. 



Labyrinth III: {figures 5 and 6) . Figure 5 is taken from Series 

 X 7 A, slide 4, row 2, section 4. In the reconstruction of this 

 labyrinth there is apparently nothing abnormal. And on exam- 

 ination of the section the only departure from the normal is a 

 slight deficiency in the cartilaginous capsule in the region of the 

 lateral center. The parabasal plate seems normal. The gan- 

 glion shown in figure 5 is the prootic near its junction with the 

 acoustic ganglion. The section passes through the endolym- 

 phatic sac, the cms commune and the lateral semicircular canal. 

 It shows the intimate relation existing between the endolym- 

 phatic sac with the chorioidal membrane. 



Labyrinth IV: (figures 7 and 8). Figure 7 is taken from Series 

 X 11 B, slide 3, row 1, section 5. This section was selected be- 

 cause it shows the characteristic protrusion of the lagena on the 

 ventromedian wall. The section is toward the caudal end of the 

 labyrinth and passes through, besides the lagena and large vesti- 

 bule, the posterior canal and the bulging caudal edge of the lateral 

 canal. Sections a little in front of this show the lateral canal 

 opening into the vestibule. Evidently in the process of trans- 

 planting this vesicle some injury was inflicted on the cells that 

 were to form the middle part of the median surface. The result- 

 ant defect includes the absence of the endolymphatic appendage 

 and a marked imperfection in the cms commune. Otherwise the 

 general form of the labyrinth is quite perfect, as can be seen in 

 figure 8. 



Labyrinth V : {figures 9 and 10). Figure 9 is taken from Series 

 X 1 B, slide 2, row 3, section 5. The section passes through the 

 endolymphatic sac, the short cms commune, and the lateral 

 canal. The lateral vestibular wall is thin and distended and 

 represents the dropsical type, which is a common deformity. 

 There is a large acoustic ganglion connected centrally with the 

 brain. This section shows well the relation between the endo- 

 lymphatic sac and the chorioidal membrane. In figure 10 the 

 shading of the lateral vestibular wall makes it look thinner than 

 shown in the model and does not give the swollen appearance it 



