158 



Papers from the Department of Marine Biology. 



The disks were quickly narcotized on being put into sea-water to 

 which had been added enough CO 2 to change the hydrogen-ion con- 

 centration to that shown by the water in the jars in which the half- 

 disks had ceased pulsating. It seems apparent, therefore, that narcosis 

 had been caused entirely by the increase in C0 2 and not by accumula- 

 tion of other waste products of metabolism, or by a decrease in the 

 amount of oxygen available for respiration. 



Table 11 shows the results of a typical experiment for determining 

 the total metabolism of active and activated halves of the same disk. 

 The hydrogen-ion concentration is given in terms of the P H numbers of 

 Sorensen. The sea-water at the beginning of the experiment had a 

 hydrogen-ion concentration of P H = 8.1 (C H = 0.793 X10~ 8 ). 



TABLE 11. 



These experiments were not carried out in sufficient detail to deter- 

 mine the regular course of respiration or the normal respiratory 

 quotient under the influence of varying hydrogen-ion concentration, 

 their aim being to determine the influence of the sense-organs on the 

 rate of total metabolism. 



The differences due to muscular activity conform to those obtained 

 from the measurements of rate of regeneration and loss of weight during 

 starvation. The amount of respiration of an active half-disk was 

 invariably as great as its activated mate in spite of the great differences 

 in muscular activity. Indeed, in only a very few instances did the 

 normal active specimen show as low a C0 2 production as the more 

 rapidly pulsating activated half of the same disk. 



The activated half-disks were narcotized when the hydrogen-ion 

 concentration of the sea-water in which they were contained had 

 reached about 0.126X10" 7 (P H = 7.9). In fact, a greater concentra- 

 tion of hydrogen ions was seldom reached hi the water in which the 

 activated disks were kept, as after the animals had been sufficiently 

 narcotized to cause the cessation of pulsation other metabolic activities 



