450 GEORGE A. BAITSELL 



The above view regarding connective tissue formation is clearly- 

 set forth by jMall ('02) who says:^ 



In very early embrj'os the mesenchj-me is composed of individual 

 cells which increase rapidly in protoplasm and then unite to form a 

 dense syncytium. The protoplasm of the syncytium grows more 

 rapidly than the nuclei divide, so that in a short time we have an 

 extensive syncytium with a relatively small number of nuclei. In its 

 form the syncytium appears as large bands of protoplasm with spaces 

 between them filled at times with cells and at other times with fluid. 

 The second condition we have in the umbilical cord of young human 

 embryos. About this time the protoplasm of the syncytium differen- 

 tiates into a fibrillar part, which forms the main portion of the syn- 

 cytium — the exoplasm — and a granular part, which surrounds the 

 nucleus — the endoplasm. 



The view of Mall, as stated above, is in quite close agreement 

 with that of Hansen ('99 and '05) which is based upon his work 

 on the development of cartilage. He believes that,^ in many 

 cases, it is not possible to distinguish between protoplasm and 

 ground substance and also that^ cells of cartilage are to be con- 

 sidered as an endoplasm and the ground substance as a common 

 ectoplasm which is more or less independent of the endoplasm. 



In the concluding section of this paper will be found an analysis 

 of these two theories and a discussion of the relations shown to 

 them by the results obtained from the present work. It may, 

 however, be stated at this time that the results reported in the 

 present paper^ strongly support the intercellular theory of con- 

 nective tissue development, and furthermore they show that 

 the process of connective tissue formation closely resembles, 

 morphologically at least, the formation of fibrous tissue by trans- 

 formation of a plasma clot. 



1 Mall, 1902, p. 331. 



2 Hansen, 1S99, p. 434. 



3 Hansen, 1905, p. 747. 



^ A report of this work was given at the meeting of the National Academy of 

 Sciences held in New Haven, Nov., 1919, and an abstract of the work is pub- 

 lished in the Proceedings of the National Academy, 1920, vi, 77. 



