410 Dr. C. Shearer. Heat Production and Oxidation 



by grants from the Government Grant Committee of the Eoyal Society, and 

 from the London Hospital Medical College Eesearch Fund, and part of it 

 was given by Mr. H. S. Souttar. 



KEFERENCES. 



(1) H. E. Eoaf, 'Roy. Soc. Proc.,' B, vol. 86, p. 215 (1913). 



(2) H. E. Eoaf, ' Journ. Physiol.,' vol. 48, p. 380 (1914). 



(3) C. S. Sherrington, "Mammalian Physiology," 'Clarendon Press,' Oxford, 1919, p. 117. 



On the Heat Production and Oxidation Processes of the Echino- 

 derm Egg during Fertilisation and Early Development. 

 By C. Shearer, F.R.S. 



(Received March 25, 1922.) 

 (From the Biochemical Laboratory, Cambridge.) 



Introduction. 



In the following experiments an attempt is made to measure the heat 

 liberation of the ovum on fertilisation and early development, and to 

 correlate this with the amount of oxygen consumed and the carbon dioxide 

 given off at the same time. New methods hitherto unused for this purpose 

 have been employed. The question has already been investigated by 

 Meyerhof (1) in an extensive paper published in 1911. He determined the 

 heat production and the oxygen consumption of the egg of the sea-urchin 

 Strongylocentrotus on fertilisation and early development. The heat production 

 was measured directly by means of a finely divided Beckmann thermometer, 

 while the eggs were contained in a small closed vacuum flask completely 

 submerged in the water of a carefully regulated thermostat. The oxygen 

 consumption of the eggs was at the same time determined at intervals of an 

 hour, by the titration of the sea-water in which the eggs were kept with 

 sodium thiosulphate by the Winkler method. 



The heat given off by a known quantity of eggs expressed in gram 

 calories per hour, divided by the amount of oxygen consumed in the same 

 time expressed in milligrams, gave him a calorific quotient which he calls 

 *' Q." This he found for the early stages of segmentation to be about 2*75, 

 but if the heat of solution of carbon dioxide to form bicarbonate with the 

 sea-water is taken into consideration this value becomes 2 - 6. This figure is 



