EXPERIMENTS UPON SURVIVING TISSUES 337 



consider the possibility of a relation with such substances of 

 the rather inconstant effects of the activators which Cohn- 

 heim and his followers have noted. 



All in all the writer believes that the expectation of 

 nearer approach to the secret of sugar catabolism in the 

 living body by experiments upon tissue pulp and expressed 

 juices is at the present unfortunately decidedly depressed. 

 It was both logical and essential in forcing the path along 

 this way to make and perseveringly repeat the experiment. 

 But it is quite as logical after being quite convinced of the 

 impracticability of this route of approach to look about for 

 other paths which lead further. 



Experiments upon Surviving Tissues. A more promis- 

 ing way is apparently to be found in perfusion of living 

 organs removed from the body. Occasion has been taken 

 in a previous lecture to state in detail the fact that in 

 E. Gottlieb's laboratory and elsewhere it has been found 

 possible to measure continuously the amount of sugar used 

 by the beating mammalian heart artificially perfused. Ref- 

 erence has already been made, too, to the expectations we 

 are justified in cherishing for the pancreatic problem by ap- 

 plying the fine perfusion methods of E. H. Starling. Oppor- 

 tunity may be taken here, moreover, to refer to the important 

 experiments of the American, McGuigan, who perfused or- 

 gans with blood diluted with Einger-Locke solution and 

 mixed with different kinds of sugar, and then calculated the 

 amount of sugar consumed (with reference to the amount 

 of glycogen shown before and after perfusion) . His experi- 

 ments show that living muscles are able to induce a rapid 

 combustion of dextrose, laevulose and galactose, but not 

 maltose, and that this is true to a greater degree when the 

 muscle is in activity than when at rest. However, in perfu- 

 sion experiments on dead muscles, which, of course, should 

 always offer more natural and more favorable experiment- 

 conditions than a ground-up muscle or an expressed juice, 



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