392 POPULAR SCIENCE MONTHLY 



different in character from that implied by the hypothetical trans- 

 formation of absorbed proteoses and peptone in the mucous membrane 

 of the intestine. Further, there is suggested a far-reaching application 

 of this synthetical power in the construction of tissue protein through- 

 out the body. 



Let us grant that in the intestinal walls or elsewhere the serum 

 albumin and globulin of the blood are constructed de novo from the 

 many simple fragments split off during the processes of digestion, what 

 then is the origin of the many different forms of protein, nucleoprotein, 

 etc., which characterize the various tissues and organs of the animal 

 body? Do these result from simple transformation of the blood pro- 

 teins which, as we are wont to say, nourish the active cells of the body 

 and serve as pabulum for the hungry tissues ? 



No account has been commonly taken of the fact that these proteins of the 

 blood must be taken to pieces and again put together, rearranged on a different 

 plan, if they are to serve for the making of proteins and nucleop rote ins in the 

 cells of the muscles and other organs in which the destructive changes of life 

 are felt. The proteins circulating in the blood are a currency which is not 

 legal tender. And no account has been commonly taken of the familiar fact that 

 when no food is obtainable, certain organs maintain for themselves a normal 

 composition at the expense of the substance of other organs. When the spleen, 

 liver, or the muscles of the limbs dissolve away in starvation, the heart feeds 

 on what they supply. Are the proteins of these organs converted into serum 

 albumin and globulin, or are they melted down by autolytic processes into the 

 same cleavage products as are formed in the digestion of food, and in this form 

 thrown into the circulating blood, which is thus in a position to supply the 

 heart and diaphragm with just what they are accustomed to receive in the 

 blood from the digestive organs? (Leathes.) 



In attempting to answer this question, I need only call to your 

 attention the many data collected during the past few years concerning 

 autolysis in general; in which it has been found that practically all 

 the organs of the body are capable under suitable conditions of under- 

 going auto-digestion, with formation of essentially the same cleavage 

 products as result from the breaking down of proteins in the gastro- 

 intestinal tract. Further, the ferments or enzymes that are responsible 

 for these autolytic transformations have been in some measure isolated 

 and separated from each other. When these facts were first brought 

 to light, it was assumed that the changes in question were mainly at 

 least the result of post-mortem conditions, but there is no justification 

 for such an assumption. Intracellular enzymes are a part of the nat- 

 ural equipment of living cells, and metabolic events, nutritional 

 changes, such as characterize the life and activity of tissues and organs 

 in general, are undoubtedly due to the power of these agents, normally 

 controlled, however, by a variety of conditions that must tend to bal- 

 ance conflicting interests. We can well imagine that in the life and 

 death of tissue cells autolytic decompositions are constantly taking 



