COMPARATIVE STUDIES ON RESPIRATION 

 XX. The Cause of Partial Recovery. 



By O. L. INMAN. 

 (From the Laboratory of Plant Physiology, Harvard University, Cambridge.) 



(Received for publication, September 29, 1921.) 



New questions regarding the mechanism of injury and recovery- 

 have recently arisen. It has become apparent that, contrary to the 

 accepted view, recovery from injury may be either partial or com- 

 plete, according to circumstances. This conclusion was drawn from 

 investigations on electrical conductivity by Osterhout^ and has been 

 confirmed by the experiments on respiration carried out by the 

 writer.2 



A question of especial interest is whether partial recovery is due 

 to the death of certain cells or to a lowered rate of metabolism of all 

 the cells which make up the tissue. The writer has endeavored to 

 throw hght on this question by determining the number of cells that 

 survive after exposure to a toxic agent and by comparing the rate 

 of respiration before and after such exposure. 



The material used in these experiments was a unicellular alga, 

 Chlorella. It was isolated from the soil by Dr. Schramm and grown 

 on agar, free from bacteria and other organisms. The agar was pre- 

 pared in the following manner. 



Agar 10 gm. 



Calcium nitrate 1 .026 gm. 



Magnesium sulfate (hydrated) 0.2 gm. 



Dipotassium phosphate 0.2 gm. 



Calcium chloride (anhydrous) 0.1 gm. 



Ferrous sulfate trace 



Distilled water 1000 cc. 



' Osterhout, W. J. V., /. Gen. Physiol., 1920-21 , iii, 145, 415, 611 . 

 »Inman, O. L., /. Gen. Physiol., 1920-21, iii, 663. 



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