52 



JOSEPH HALL BODINE 



rate of CO2 output of the animals with blackened eyes dropped 

 characteristically and remained so. After several hours the var- 

 nish on the eyes became dried and brittle and could easily be 

 scraped off with fine forceps, leaving the eyes again exposed. 

 Immediately after removal of the varnish the rate of CO2 output 

 increased considerably, being slightly higher than the original 

 normal rate. This increased rate, however, lasted only a rela- 

 tively short time, when the normal rate was resumed. Figure 2 

 shows graphically the results of such an experiment. 



Fig. 1 Curve showing the effect of blackening the eyes and of decapitation 

 on the rate of CO2 output. Based on average of fifty individuals. Ordinates 

 represent the rate of CO2 output. The normal rate (which is taken as 100 per 

 cent in each case) corresponds to the time to produce a definite amount of CO2 

 (the same amount in any experiment). Points on abscissas indicate different 

 experimental condition of animals, A'', normal animals; A, animals with eyes 

 blackened; B, decapitated animals. 



That the decrease in rate of CO2 output was a permanent con- 

 dition as long as the eyes were blackened is shown by the follow- 

 ing. Several individuals of the same species and kept under as 

 near the same conditions as regards food, etc., as possible were 

 taken and their rates of CO2 output determined. Half the indi- 

 viduals were then subjected to the eye-blackening process and 

 the characteristic decrease in rate of CO2 output obtained. The 

 remaining individuals were kept as controls. All the animals 

 were starved for twenty-four hours under the same laboratory 



