134 



GEORGE FRED SUTHERLAND. 



10 (six days' regeneration) shows the cells in one part of the cord 

 stretched out to such an extent that vacuoles are left between the 



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 



Fig. 12. Curve giving the number of mitotic divisions in that part of the spinal 

 cord within 3 mm. of the edge. Beyond 3 mm. the mitoses are scattered. An 

 abscissa represents the period of regeneration and the corresponding ordinate gives 

 the average number of mitoses found in the individuals killed at the end of that 

 period. 



cells. It is during the period from four to sixteen days that most 

 of the increase in length takes place, by active proliferation and 

 migration of cells. 



IV. Discussion. 



I. Amitosis and Fragmentation. 



Fraisse in describing the regulative process at about two days 

 after the operation, says; "Bereits friiher machte ich darauf 

 aufmerksam, dass am Wundrande eine starke Auswanderung von 

 Leukocyten stattfindet, und dass diese es sind, welchen vor alien 

 Dingen die Bildung des homogenen, lymphartigen Saumes, 

 welcher zuerst die wunde bedeckt, zuzuschreiben ist. Das 

 Riickenmark geht nun an meinen Schnitten bis dichte an diesen 

 homogenen Saum heran, und die Elemente, welche es zusammen- 

 setzen, lassen sich immerhin noch nach 24 Stunden auch an 



