ii CHANGE OF FORM IN MUSCLE DURING ACTIVITY 95 



Eanke in particular has pointed out, i.e. the accumulation of 

 certain disintegration products (56). 



Any considerable aggregation of the so-called D-products in 

 muscle can only occur in preparations that are excised and with- 

 drawn from circulation, and the rapid appearance of fatigue in 

 such a muscle must at least in part be due to this factor also. 

 The restorative effect of transfusion with (arterial) blood can only, 

 however, consist in a minor degree in the elimination of the D- 

 products (COo, lactic acid, KH.,P0 4 , etc.), for otherwise a washing- 

 out of the muscle with any indifferent fluid (e.g. physiological 

 salt solution) would have the same effect as the infusion of blood, 

 which never is the case. 



Unquestionably, therefore, the blood carries to the exhausted 

 or dying muscle, matters which are essential to the restora- 

 tion of its working powers. With regard to the necessary 

 quality of the blood, we can speak with certainty of a few 

 elements only oxygen, e.g., which is indispensable to the main- 

 tenance of excitability and capacity of movement in all living- 

 substance. 



Owing to the relatively large bulk of an excised cold-blooded 

 muscle it is capable of little, or hardly any, physiological ex- 

 change with the atmosphere, which is only possible on the surface, 

 and accordingly the presence or absence of free oxygen in the 

 neighbourhood of such a muscle exercises a negligible in- 

 fluence upon the conservation or restoration of its excitability. 

 In fact, Hermann (4, p. 132) finds that frog's muscle retains its 

 excitability in perfectly indifferent gases (N, H), and still more in 

 vacua, as long as, or longer than, it does in the air. The transfusion 

 of nutritive fluids containing oxygen, on the other hand, produces 

 a very different effect. In this case a lively exchange of gases 

 goes on between the blood, which circulates freely inside the 

 muscle, and the muscle-substance, and here the beneficial effect 

 of oxygen on excitability may be determined with certainty. 

 Bichat was aware that venous blood could not preserve muscular 

 excitability as well as arterial blood, while Ludwig and Schmidt 

 (57) subsequently showed that the artificial circulation in warm- 

 blooded muscles of blood that had been freed from oxygen had 

 no more effect than if there had been no such circulation ; the 

 excitability in fact disappears more quickly in some cases when a 

 muscle is injected with venous blood than when it is quite blood- 



