26 



have called altcMition to Iho fact that soniclhin<» similar 

 inusl ap|)l> in man since the rate ol" cicatrizalioii of liuinan 

 woiiiuls. measured aceiiralely. is round lo vary inversely 

 with the aj^e of tlu' |)a[ient i)y applying liie dn X o i'l y's '^o) 

 tormulai" lor eiealrizalion ol' wounds to Ilie rale of growth 

 of the libroblasls. 



The changes in rale ol" growth seem lo be one of Ihe most 

 important I'esponses of the xarious tissues in culture when 

 Ihe conditions are somewliat changed, especially when 

 the changes an- of a chemical or biochemical nature. C-han- 

 ges in the composition of the culture medium, adding bac- 

 terial proteins, or treating the various compounds by heat 

 or chemicals, and so on, result apparently only in changes 

 in the rale of gi'owth and ai)parenlly not in changes 

 in morphology, at least not lo a noticeable extent ^'•>^) i^^'^). 

 Therefoi'e Ihe determination of rale of growth becomes high- 

 ly im])()i-lanl. It seems thai when ciianges in the culture 

 medium are of a more mechanical nature morphological 

 changes in the cells occur, L. L o e b, ^ts) sts) U h 1 e n- 

 h u t h «8). 



It has already been observed by Cohnheim that Ihe 

 leucocytes when they apj)ear in the cornea under con- 

 ditions oJ" inflammation become spindle-shaped and fusiform 

 as fibroblasts. Later L e o L o e b ^'^'^) observed in epithelial 

 cells similar changes when, under experimental conditions, 

 he examined the migration of these cells in blood coagulum 

 or agar. Recently E. U h 1 e n h u t h ^^^) studied the mor- 

 phological changes in epithelial cells IVom frogs when cul- 

 tivated in culture media of varying consistency. The chan- 

 ges in sha])e of the cells show that Ihe mechanical factor 

 plays an important role hei'e. The leucocytes in the inflamed 

 cornea become elongated on account of the mechanical 

 structure of the cornea; Ihe same thing happens to epithelial 

 cells in the dense fibrin meshwork in the clot. No doubt 

 the outer appearance of the tissue cells de- 

 pends mainly on the a I'c h i I e c I u I'e of the sup- 



