PEPTOLYTIC POWER OF BLOOD SERUM 95 



the highly differentiated organs of man, is in reality a chem- 

 ical laboratory, in which proteolysis is going on in myriads 

 of different forms ! Think of the crudeness of our attempts 

 to classify all these heretofore ! Many a time in the last ten 

 years when busily engaged in collecting material for a com- 

 parative chemical physiology of the lower animals, has the 

 author lost his temper on seeing how learned men, in endless 

 controversy as to whether this or that secretion possess a 

 ' ' peptic " or ' ' tryptic" character, quarrel among themselves, 

 without the least thought on the part of any one of them 

 of some better trophy than that of their trivial "clearly 

 reddened " or "distinctly blued " litmus papers. It is to be 

 hoped that as the methods elaborated by Abderhalden come 

 into general appreciation it will all be very different. It is 

 quite likely that these methods will not be as easy of prose- 

 cution as litmus-paper processes ; and it is to be expected, 

 too, that facility in them will require progressively a more 

 and more comprehensive chemical training. 



Peptolytic Power of Blood Serum. In conclusion refer- 

 ence may again be made to the promise held out by the recent 

 methods of study, of information regarding the active 

 proteolytic agencies in the blood serum. Abderhalden and 

 his collaborators have discovered that subcutaneous or in- 

 travenous injection of specifically foreign but not of specifi- 

 cally homologous protein increases the peptolytic capacity 

 of blood serum. The normal serum of a dog, for example, 

 is incapable of catabolizing silk-peptone. Its proteolytic 

 ability is apparently increased by parenteral introduction of 

 horse serum, gliadin, casein, diphtheria toxin, tuberculin, 

 but not by dog serum. Serological studies in this line, ap- 

 plying the optical method, are full of suggestive promise for 

 many of our important problems (as anaphylaxis). It is a 

 matter of regret that further discussion of the theme cannot 

 be pursued ; the whole subject is thus far too undeveloped 

 to permit a definitive conclusion. 



