v INTEKNAL KESTITUTIVE SECRETIONS 289 



undergoing more or less advanced peptonisation and hydrolysis. 

 Schmidt -Mlilheim's researches in this direction are not very 

 convincing. It seems probable that the degree of peptonisation 

 and hydrolytic cleavage into amino-acids of the proteins varies 

 considerably within wide physiological limits. 



With this question we must associate the effects of total 

 or partial removal of the pancreas, in relation to the absorption 

 and utilisation of alimentary protein. According to Minkowski 

 and Abelmanu (1890), a dog wholly deprived of its pancreas may 

 absorb and utilise on an average 44 per cent of the flesh ingested ; 

 when the extirpation has been incomplete it may even make use 

 of 54 per cent. When a little pig's pancreas is fed to the animal 

 along with the meat, the amount of protein lost with the faeces 

 is conspicuously diminished. According to Landmeyer's latest 

 experiments (1895), 62-70 per cent of the proteins can be utilised 

 after incomplete ablation of the pancreas. Nothing definite 

 can, however, be concluded from this fact as to the extent under 

 normal conditions of the peptonisation of ingested proteins and 

 their cleavage into amino-acids. It is certain that a considerable 

 portion of them must be subjected to this process not only to 

 accelerate absorption, and thus increase the amount utilised by 

 the body, but also, by means of the molecular aggregates repre- 

 sented by the amino-acid group, to make possible the synthetic 

 constitution of the complex proteins which are specific to organisms 

 of different species or genera. 



The process by which the proteoses, peptones, and amino-acids 

 are utilised by synthetic processes is very remarkable. They are 

 largely regenerated into natural protein (probably into serum- 

 albumin) during their passage through the mucous membrane, by 

 the anabolic activity of the epithelium. The experimental data on 

 which this important conclusion rests are numerous and agree 

 well together. 



(a) Proteoses and peptone are never found in the blood or 

 lymph, even when these fluids are examined during absorption, 

 after an abundant digestion of proteins. Schmidt-Mulheim and 

 Hofmeister stated that peptone could be detected in blood-serum in 

 a maximum amount of 0'02-0'05 per cent, but more exact experi- 

 ments subsequently undertaken by Neumeister (1888) excluded 

 even this small amount of peptone. Under the best conditions 

 of experiment, the biuret test is always absolutely negative, both 

 with lymph and with blood-serum. 



(5) When proteoses and peptone are injected directly into the 

 blood, they immediately disappear from it (Fano), and pass into 

 the urine as bodies foreign to its normal composition (Hofmeister, 

 Neumeister). If a considerable quantity be injected, they induce 

 toxic phenomena and modify the composition of the blood by 

 rendering it incoagulable, which causes an enormous lowering of 



VOL. II cr 



