POSTURE OF MEMBRANOUS LABYRINTH 157 



resultant development of the transplanted labyrinth. These are : 

 firstly, those in which the labyrinth is nearly normal; secondly, 

 those in which the labyrinth is abnormal though the main 

 parts of it are easily recognizable; and thirdly, those in which 

 there might be some question as to the identification of the differ- 

 ent parts of the labyrinth. There are eight in the first group, 

 eight in the second group, and three in the last group. Based 

 on their order in these groups we may now proceed to the exam- 

 ination of the individual labyrinths. 



Labyrinth I: {figures 1 and 2). The photograph shown in figure 

 1 is taken from Series X 2 C, slide 5, row 3, section 7. The study 

 of this labyrinth shows only one slight departure from the normal, 

 and that concerns the Saccus endolymphaticus which lies some- 

 what cephalad to the crus commune. It is on this account that 

 it does not show in figure 1, which is directly through the crus. 

 What looks as though it might be the edge of the sac, is the pig- 

 ment layer of the skin. Aside from its slight anterior displace- 

 ment it bears the usual relation to the chorioidal roof of the 

 fourth ventricle and is normal in size. 



Labyrinth II: {figures 3 and If). Figure 3 is taken from Series 

 X 2 A, slide 4, row 1, section 3. Here as in Labyrinth I the endo- 

 lymphatic sac is slightly in front of the crus commune. The crus 

 is a little wider than in the former, so both it and the sac can be 

 seen in figure 3. This labyrinth shows no noteworthy departure 

 from the normal in either its histology or general form, aside from 

 the slight displacement of the endolymphatic sac. In the draw- 

 ing of figure 4 the groove between the ampullae of the anterior 

 and lateral canals has been exaggerated a little more than is 

 warranted by the reconstruction. In figure 3 the thickening of 

 the ventro-lateral labyrinth wall is partly due to the crista of the 

 lateral canal which it represents, and partly is due to the obliquity 

 of the section of the ampulla. The characteristic relation of the 

 endolymphatic sac to the chorioidal roof of the ventricle can be 

 seen. The large ganglion on the ventro-median wall of the laby- 

 rinth is the prootic ganglion ; the acoustic ganglion lies in a simi- 

 lar position but is found in the more caudal sections. Some of 



