594 PRINCIPLES OF GENERAL PHYSIOLOGY 



in such cases, Meyerhof found the caloric quotient raised to 3'3. If the heat of 

 combination of ammonia with carbon dioxide be deducted, the value falls to 2 '95 ; 

 but this is the maximum deduction permissible, so that the value is certainly 

 raised above the normal one. 



As to the meaning of the low value of the caloric quotient, no evidence of the 

 presence of carbohydrate was to be found, and there was no breakdown of protein. 

 Fat, on the other hand, was found in sufficient amount to cover the heat produced. 



Further experiments (191 '2, 1) were made with nucleated blood corpuscles of 

 birds. In this case, a "normal" caloric quotient of a value between that of 

 protein and fat was found. As Meyerhof remarks (1912, 2, p. 1), it can scarcely 

 be an accidental coincidence that, when the normal caloric quotient was found, 

 the cells were in a stationary condition, in the other case in active multiplication. 



In the case of aerobic bacteria, Meyerhof (1912, 2) finds that the caloric quotient 

 is from 4 '5 to 4'7, whether growth is in progress or inhibited by deficiency of food 

 material, being rather higher in the latter case. This high quotient seems to be 

 due to reactions in the nutrient solution brought about by products of bacterial 

 action. 



Horace Brown (1914, p. 223) finds that the heat production of yeast, as grown 

 in fermenting solutions, is, weight for weight, somewhere about seventy times as great 

 as that of a man at rest. An explanation of this relatively enormous metabolism is 

 suggested on the basis of the abnormal conditions under which yeast is cultivated 

 for industrial purposes, as compared with its natural habitat on the outer skin of 

 fruits. It must be remembered that we know now that there is no inverse 

 proportion between fermentation and growth. In absence of oxygen, no growth 

 takes place, but, as Pasteur showed, the fermentation process goes on with vigour. 

 The cells remain constant in mass and in composition, so that no energy is needed 

 for growth, yet, as Horace Brown puts it (p. 224), " there is an enormous 

 activity in the metabolic mill, through which continues to pass an amount of 

 substance which may amount to several times the mass of the cell in a few hours." 



Further considerations on the question of anaerobic existence will be found in 

 the next chapter. 



In the paper referred to (p. 226), Horace Brown states that he has obtained 

 evidence that less heat is evolved from the same amount of sugar fermented, when 

 growth is taking place, than in its absence. Quantitative measurements of this 

 kind would give, of course, what might be called the "heat of formation" of 

 yeast. 



THE OXIDATION POTENTIAL OF CELLS IN THE ORGANISM 



The experiments of Ehrlich (1885) are of much interest in this respect, 

 although they are not, in all cases, easy to interpret. Two dyestuffs were used in 

 intravenous injection, both capable of oxidation and reduction. One of them, 

 alizarin blue, is reduced with difficulty ; it requires boiling with caustic alkali and 

 glucose. The other, indophenol blue, is more easily reduced. 



We saw in our first chapter that living protoplasm itself does not stain with 

 soluble dyes ; the two dyes used in Ehrlich's experiments were, accordingly, 

 introduced in the form of suspensions, or colloidal solutions, and the particles were 

 then taken up by the cells of various organs and found therein subsequently, either 

 as the reduced, colourless derivative, or the oxidised, blue one, according to the 

 oxidation potential of the cell system. 



Alizarin Blue. This dye does not become reduced in the blood, but is reduced 

 in the liver, the renal cortex, the Harderian gland, and the lungs. The amount 

 taken up depends, as would be expected, on the permeability of the cell membrane. 



Indophenol Blue. The heart and the brain, together with certain voluntary 

 muscles, such as the diaphragm and the eye muscles, are blue. The renal cortex 

 and some other secreting glands also do not reduce the dye. By all other organs 

 it is reduced. 



In general, it may be said (Ehrlich, 1885, p. 109) that the reducing power of 

 protoplasm lies between that required by alizarin blue and by indophenol blue. 



