630 THE RESPIRATION AND [pt. m 



simply due to the suppression of cleavage was apparent from the 

 fact that some of the toxic agents themselves (such as chloralhydrate) 

 depressed cleavage. These questions were dealt with for some further 

 time in the papers of Warburg; Loeb & Wasteneys and Meyerhof. 

 Other workers who have studied the effect of various salts on the 

 respiration of echinoderm eggs are Loucks & de Graff. 



More important embryologically were the observations in which 

 Warburg showed that not only phenylurethane would dissociate the 

 respiratory from the morphological process, but also many other 

 agents, such as narcosis with ammonia. The oxidative intensity, as 

 judged by the intake of oxygen, remained unchanged although 

 morphological development might stand quite still. Moreover, the 

 respiratory rate could be raised to very high levels through the action 

 of hydroxyl ions and traces of heavy metals without any morpho- 

 logical development going on at all. Cyanide here took a special 

 position for, penetrating into the cell, it decreased the respiration-rate 

 considerably, and also decreased the development-rate, not producing 

 any deformations, but simply slowing down the normal processes. 



Respiratory rate 

 c.c. oxygen 

 per hour per 

 28 mgm. nitrogen Cleavage 



In sea water ... ... ... 0-372 Normal 



In JVy 1 00,000 sodium cyanide ... 0-120 Very slow 



In JV/io,ooo „ ... 0-072 None at all 



Cyanide and temperature were thus the only two agents found by 

 Warburg which equally affected respiratory rate and morphological 

 development. 



That the increase in oxygen consumption did not rise parallel 

 with the increase in nuclear material was fully confirmed in Warburg's 

 third paper. The respiration-rate for Strong^locentrotus lividus eggs in 

 the 2-cell stage was 0-438 c.c. oxygen, and in the 64-cell stage 0-612, 

 an increase of only about 1-5 instead of 32 times. A few experiments 

 in which the carbon dioxide output was estimated gave quite 

 similar results; thus in one experiment the respiratory rate for 

 oxygen was 0-20 c.c. of oxygen and o-i8 c.c. of carbon dioxide. 

 Not enough work on these lines was done, however, to lead to any 

 determinations of respiratory quotient. Possible respiratory dif- 

 ferences between monospermic and polyspermic eggs were in- 

 vestigated by Warburg, and found to be slight — thus the respiratory 



