536 STUDIES ON RESPIRATION. XVI 



the depression of the freezing point was approximately determined 

 by means of a Beckmann apparatus. The temperature of these ex- 

 periments was 18° dz 2°C. 



Fig. 1 shows quite clearly that in higher concentrations, e.g. specific 

 gravity 1.130 (A = —9.37) there was always a decrease in the amount 

 of carbon dioxide given off. It is also shown that with hypotonic 

 solutions the decrease in respiration is not so pronounced. 



100% n 



50 - 





0' 



-P^i , , , 



10023' 4.0062 1.0242 1.062 1.13 Sp.gr. 



■0.187 -0.460-1.81 -5.45 -9.37 A 



Fig. 2. Curves showing the rate of respiration of Laminaria in relation to the 

 specific gravity and freezing point depression of sea water. The upper curve 

 shows per cent of respiration at end of 10 minutes for all concentrations and dilu- 

 tions. The lower curve shows the same at end of 40 minutes. The point at 

 the intersection of the curves represents normal sea water. These curves are 

 constructed from the same data as the curves in Fig. 1. The ordinates repre- 

 sent rate of production of CO2 expressed as per cent of the normal. Abscissae 

 represent specific gravity; under each of the numbers denoting specific gravity 

 is noted the corresponding freezing point depression. 



Fig. 2 shows the relation between the specific gravity of the solution 

 and the respiration to be almost a linear function in the case of hyper- 

 tonic solutions. In the case of h3rpotonic solutions it is not so simple. 



Experiments of a similar nature were carried out on wheat seedlings 

 in which hypertonic solutions alone were used. Hypertonic solutions, 



