356 



PHYSIOLOGICAL. KEGULATIONS 



removal is small (fig. 177) ; but the whole return is in no instance 

 equal to the initial deficit. 



By transformation of coordinates a half of an equilibration dia- 

 gram is obtained (fig. 178). The curves may be convex, concave, 

 or straight depending upon the stage of recovery. But at all stages 

 the rates of tissue construction are of lower order of magnitude 

 than those encountered in any recovery that has been thus far 

 considered. Every biologist knows that regeneration is a slower 

 process than recovery of water content after privation. It is now 



Area of Wound — cm.* 



Fig. 179. Eate of scar-formation in skin in relation to mean area yet to be covered. 

 Man. Measurements of area of wounds were made every 96 hours, and the first two 

 intervals recorded in each of 20 individuals recovering from war wounds are indicated. 

 Ages 20 to 40 years; no diversity with age was apparent in the data as plotted. The 

 line corresponds to the equation Eh = 0.006 SO''. Data of Carrel and Hartmann ( '16) 

 and Noiiy ('16a and '16b). 



possible to compare them quantitatively; adult Rana shows maxi- 

 mal velocity quotients for water replacement (fig. 70) of 0.7/hour, 

 while larval Rana shows maximal quotients for tail replacement of 

 0.0014/hour. The factor of contrast is about 500. 



(2) Human skin. In man, parallel data measure the regenera- 

 tion of wounded tissues. The wounds studied involved more tissue 

 than could properly be called skin ; the amount of closure was the 

 quantity actually measured, and not all closure was by formation 



