MUCOPOLYSACCHARIDES OF CONNECTIVE TISSUE 343 



polymer, with attendant increase either in the number of the polymer molecules 

 present and/or large increase in their molecular weight. 



DORFMAN : I should point out that we have shown net synthesis of hyaluronic 

 acid. 



Marshall: Dr. Dorfman's work is tremendously stimulating to some of us 

 concerned with very different problems in cell physiology. May I add to Dr. 

 Porter's comment a remark based on experience with amoebae ? We have come to 

 view the amoeba surface as a combined structure, with an inner membrane and 

 an outer mucoid coat. Both components must be thought of in dynamic terms, 

 because in amoebae we observe new formation and expansion of surface without 

 the appearance of successive layers, such as Dr. Porter has just described in 

 chondrocytes. Rather there appears to occur some sort of interstitial formation of 

 new membrane and new coat material. I don't know whether the amoeba surface is 

 unusually labile, or unusually rapid in turnover compared to that of other cells, 

 but it suggests an even more dynamic way to conceive of the passage of substances 

 in or out of a cell, without there being at any time a stable structure in which holes 

 must appear. 



