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the methods of analysis employed it was not detected. On 

 the other hand, these amino acids can lose their nitrogen fairly 

 readily through the action of the body tissues, as has been 

 demonstrated by the work of Jacoby * and of Lang. 2 Lang 

 showed that if one mix various amino acids with chopped-up 

 animal tissue, such as liver, spleen, intestine, etc., the amino 

 groups are split off. For instance, glycocoll was found to give 

 up its nitrogen freely when mixed with liver, but even more 

 freely when in contact with intestinal tissue. Tyrosin could 

 be attacked by the liver, but only with difficulty. Leucin, on 

 the other hand, was fairly readily decomposed by that organ, 

 and so on with other amino acids. Thus it may be that the 

 absorption of the decomposition products is in the form of 

 bodies nitrogen free, as acids of the fatty acid series such as 

 lactic acid. In favour of this view, perhaps, the work of Nencki 

 and his co-workers may be cited. Nencki, Pawlow, and 

 Zaleski 3 showed that the blood taken from the portal system 

 contains three to four times more ammonia than the systemic 

 arterial blood. This is extremely well marked where the 

 animal has previously been fed on a meat diet. This ammonia 

 might be regarded as that split off from the amino acids during 

 or after their course through the intestinal wall, and which, 

 for the most part, is being hurried to the liver, there to be 

 converted into urea for excretion. It must be remembered, 

 however, that according to Horodynski, Salaskin, and Zaleski 4 

 starvation has practically no effect on the amount of ammonia 

 in the arterial blood, and that there is only a very slight 

 reduction in the amount present in the portal blood. 



Others, again, hold that there is no such simple absorption, 

 but that as soon as they are absorbed the products of digestion 

 undergo synthesis, and in this reperfected form reach the body 

 circulation. As regards this question of regeneration of a 

 coagulable protein, Dr. Leathes and the writer (I.e.) were quite 

 unable to detect any such increase, although this question was 

 carefully gone into. Neither by an estimation of the total 

 nitrogen before and after absorption nor by controls carried 

 out by observations on the amount of haemoglobin, were we 



1 Jacoby, Zeit.f. physiol. Chem. 30, 1900, 149. 



2 Lang, Hofmeister's Beitriige, 5, 1904, 321. 



3 Nencki, Pawlow, and Zaleski, Schmiedeberg's Archiv, 37, 1896, 26. 



* Horodynski, Salaskin, and Zaleski, Zeit. f. physiol. Chem. 35, 1902, 246. 



