PROTEIN REQUIREMENTS 81 



(362), on the other hand, who examined the livers of fasting cats and 

 those killed about five hours after a full meal, obtained results exactly 

 contrary to those of Seitz. Schryver found that in practically every 

 liver examined (fourteen on record, eight fasting and six fed) there was 

 more total nitrogen present in the liver of the starving animal than in 

 that of the fed one. Not only was the total nitrogen increased under 

 this condition, but there was also a slight increase of the non-coagulable, 

 or as he called it, the residual nitrogen. It must be remembered that 

 in Seitz's experiments the birds were carefully fed on a high protein diet 

 for many days before they were killed, and further that retention could 

 only be shown after more or less prolonged and careful dieting. Schry- 

 ver's experiments were not carried out to demonstrate this point, and 

 therefore no care about the previous feeding was taken. Cathcart and 

 Leathes (92) have also shown that during active absorption from the in- 

 testine there is a definite amount of storing of nitrogenous material in 

 the liver. Reach (335) carried out a series of experiments to demon- 

 strate this retention of protein by the hepatic cells, but the method he 

 employed was quite different. He perfused the liver with a mixture 

 of blood, Ringer's solution and a protein-iodine preparation. He found 

 that usually there was a very marked retention of the iodine protein 

 compound in the liver in the form of the iodine protein itself; very 

 little breakdown of the protein took place, as no free iodine could be 

 detected. 



A certain amount of histological evidence has been adduced in sup- 

 port of the view that the hepatic cells form one, at least, of the 'protein 

 depots. Amongst the modern workers Boehm (70 A), in an interesting 

 investigation of the histological appearance of the hepatic cells after 

 different kinds of food and digestion products, found that the size of 

 these cells varied. The smallest cells were found after hunger, and 

 the largest after protein feeding. He further found that the structure of 

 the protoplasm differed with different foods. Feeding with alanine 

 and asparagine had no definite effect on the hepatic cells. Reichenau 

 (336 A), maintained, however, that the histological evidence was value- 

 less, that, for example, the proteoses could not be shown to have any 

 marked influence on the activity of the liver. He further raised the 

 question as to the form in which the protein was retained. Was it 

 retained as protein or as protein digestion products? (see later p. 83). 



Johansson and Hellgren (213 A) have also stated from experi- 

 ments on men that all the food material including protein was not 

 used directly it was absorbed, but that after absorption it was laid down 

 in certain depots and only drawn on as required. The work of Gruber 



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