EXCAVATION OF THE CARTILAGINOUS OTIC CAPSULE 25 



more specialized tissue — in this case for the most part into a 

 \-asciihir reticuhmi. 



The perichondrium is a derivative of the periotic reticuhmi 

 and forms an outer Umiting membrane along its cartilaginous 

 margin. During the foetal period the perichondrium does not 

 rest dhectly against the true cartilage but is separated from it 

 by a zone of transitional tissue consisting partly of precartilage 

 and partly of reticulum. This transitional zone intervening 

 between the perichondrium and the surrounding cartilage was 

 observed in all of the specimens that were studied, which includes 

 fetuses up to 130 mm. CR length. Owing to the fact that the 

 perichondrium is late in making its appearance, being first seen 

 in fetuses about 70 nun. long in can take no part in the early 

 changes in the cartilaginous capsule either as regards deposit of 

 new cartilage or the excavation of cartilage that had been 

 previously laid down. 



