106 FRANKLIN PEARCE REAGAN 



taining its embryonic character and possessing several or many 

 diverse potentialities. In case of an individual cell of such a 

 tissue, one of these potentialities becomes realized while the others 

 do not; this probably takes place in response to a stimulus. It 

 seems highly probable that mesenchyme is a tissue of this sort. 

 At any rate chondrification can be artificially produced in mesen- 

 chyme to form structures whose existence was most certainly 

 not predetermined in the fertilized ovum; conversely, mesen- 

 chyme which would normally have chondrified can be prevented 

 from so doing by the removal of the exciting stimulus to chon- 

 drification. It may well be that the diverse sorts of connective 

 tissue and vascular tissue afford cases parallel to this in their 

 development. 



LITERATURE CITED 



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 Baumgarten, Dr. 1892 Beitrijge zur Entw. der Gehorknochelchen. Archiv 



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 Broman, I. 1898 tJber die Entwicklung der Gehorknochelchen beim menschen. 



Anat. Anz., 14, Ergiinzungshefte, pp. 230-236. 

 Clark, E. R. 1915 Studies of the growth of blood vessels by observation of 



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9 Heft, p. 85. 



