138 THE HUMAN MOTOR 



In spite of the diversity of the calorific co-efficients determined 

 by numerous authors, the following values, in which special 

 weight is given to Atwater's researches, are recognised : 



CARBO FATS PROTEIDS 



HYDRATES 



Heats of combustion 4-15 cal. 940 cal. 440 cal. 



Calorific powers 4-10 cal. 9-10 cal. 4-10 cal. 



Co-efficients of digestibility of 



the normal alimentation ( l ) 0-98 cal. 0-95 cal. 0-91 cal. 



97. The Origin of Vital Combustion. Where is the combustion, 

 the reaction of the combustible and the burning gas, produced ? 

 The food is absorbed by man, prepared and taken to the cells by 

 the blood : this is " assimilation " and takes place chiefly in the 

 motor organs : the muscles. Therefore it must be in the cells where 

 the blood has deposited it, and where it constitutes a reserve, 

 that the aliment undergoes combustion, because at the same 

 time, the blood brings oxygen there. The vital combustion is 

 therefore " inter-cellular," and although the motor muscles may 

 be its active origin, it is general through Dut the organism. 

 Remembering that the expenditure of energy even takes place 

 in a state of complete repose, as a consequence of life ; it is 

 clear that alimentation is, in living beings, the source of their 

 labour. The combustion and utilisation of the aliments, or the 

 " disassimilation," takes place therefore in the cells. In what 

 way does the oxygen carried by the " red corpuscles " of the blood, 

 react on the alimentary molecules deposited in the cell ? This 

 question has not received any answer, but one can imagine 

 a "condensed " state of the combustible molecules which in- 

 creases their " chemical force," or their " affinity " ( 35). The 

 matter in the red corpuscles, called " haemoglobin," easily gives 

 up its oxygen, and this " disassociation " results in the emission 

 of " nascent " oxygen which is more active than the normal gas. 



f 1 ) Wait (Bull., No. 89, p. 72, 1901 ; No. 117, p. 41, 1902 ; No. 136, p. 107, 

 1903). 



