199 



One question be still mentioned here, because I had to put it 

 already when studying this family: 



Hoiu far can the degeneration of the mesenchyme proceed in a 

 family before 07ie or more of the other germinal layers also begin to 

 degenerate? It is obvious, that precisely families with a defective 

 mesenchyme are the most suited to give an answer to this question, 

 in view of the comparatively less important functions of most of 

 the mesenchyme-organs. 



1 was able to have two members of this family and two of my 

 patients examined otologically (Prof. Burger). All four of them, 

 though they had no complaints worth mentioning, proved to be 

 suffering from a labyrinth deafness, an hereditary disease par 

 excellence. But an affection of an ectodermal organ. 



On the contrary van der Hoeve and de Kleyn found in their 

 patients who suffered from blue sclerotics and brittle bones, otoscle- 

 rosis (mesenchyme), although they could state with one patient a 

 combination of otosclerosis and labyrinth deafness. I doubted 

 however immediately, whether the affection of the organ of Corti 

 in my patients was a primary or a secondary one. For according 

 to the investigations of Quix and van Lennep the atrophy of the 

 organ of Corti, is most probably caused in some cases of hereditary 

 labyrinth-deafness (in casu the dancing-mouse) by a primary affection 

 of the stria vascularis. Now the latter is a product of the mesenchyme. 



And so at any rate the possibility is present that the affection 

 of the labyrinth in this family is a further proof of an inferior 

 mesenchyme, and the occurrence of this abnormality need not 

 lead to the conclusion that the inferiority in this family is not 

 restricted to the mesenchyme. 



