EXCAVATION OF THE CARTILAGINOUS OTIC CAPSULE 
9 
Collection, No. 719). It will be noted that the capsule abuts 
directly against the epithelial wall on the labyrinth. Around 
the margins of the capsule there is a vascular network the 
branches of which, however, do not penetrate into its sub- 
stance. In its form it is essentially the same as its antecedent 
capsule of condensed mesenchyme, but in structure it can be 
seen to be undergoing certain characteristic alterations. These 
do not occur uniformly throughout its substance but appear 
Fig. 5 Camera lucida sketches showing characteristic fields in sections of the 
otic capsule while it is in the precartilage state. Enlarged 950 diameters. The 
groups labelled A are taken from an embryo 17 mm. long (Carnegie Collection, 
No. 576). Group B is taken from an embryo 18 mm. long (Carnegie Collection, 
No. 409). 
earlier in some areas than in others. They consist of an increase 
in distance between the nuclei, together with an alteration in 
the internuclear protoplasmic network and its spaces. Whereas 
the capsule, as seen in prepared sections, has previously con- 
sisted of a mesenchymal syncytium, it now gradually loses its 
syncytial appearance. Most of the branching processes dis- 
appear and are replaced by a homogenous mass. Some of the 
processes, on the other hand, persist, and become thicker and 
more sharply outlined. These persisting larger processes usually 
exhibit a characteristic relation to the nuclei. Two or more of 
