1(12 



tlu' olil c-iilliirc medium is inlcrposcd l)cl\\i'(ii ;i piiit ol' llic 

 new medium, iu umst cjises no f^rowlli is produced in llial 

 |);ii'l W lu'ii ;i |)iece ol' plasma is lell allaehed lo liie eulUire. 

 i^i-owlli lakes place al llie edjfes lirsl. wliei'i' llie cells are 

 directly in conlact wilh llie new medium. This may he due 

 lo Iwo I'aclors; lirslly, llie old |)iece oT plasma may conlaiu 

 so many (lecomposinj* |)roducls lell o\t'r From llie lirsl 

 growlh, Ihal il produces unlavourahle condilions liom Ihc 

 very beginninji; and secondly, a purely mechanical eirecl 

 is iiroduccd, namely a shrinkaf*e or I'elraclion ol' llie plasma 

 clol which bel'ore adhered to the cover-glass, and which after 

 il has been cut shrinks on account ol" its elasticity. This 

 shrinkage changes tlu' structure and the i-elalion lietwecn 

 the fibrin and fluid and between the cells and fibrin mesh- 

 work. These facts may explain why no growth is pi'csent 

 under the condition of experiment. — By making an incision 

 in llie ex])anded j)lasiiia coagulum. possibly the fibrillary 

 slruclurt is clianged. lietraction may lake place after the 

 incision is made. It was observed that the incision created 

 a large elliptical woimd, very similai" in ap|)earance to cer- 

 tain incisions made in the skin. 



We do not know^ the final structure of the fibrin meshwork 

 and we do not know how the system of the plasma clot 

 is built up with regard lo the solid and licjuid phases. It 

 might be possible, however, that the absence of growth is 

 due to the mechanical changes. 



To return now to the experiments wilh isolated cells, it 

 is possible that the vitality of the cells suffers during mani- 

 pulation; but all signs seem to indicate perfect vitality, 

 since a lively ameboid movement is present and a (juick 

 transformation from a round cell-slia]ie to a typical spindle 

 shaped fibroblast occurs. There is. however, a possi])ility. 

 that a single cell may suffer from incai'ceration in the dense' 

 coagulum and il may be unable perhaps to produce a suf- 

 ficient liquefaction of the medium in its immediate sur- 

 roundings. 



