CHAP. IX.] THE CONTRACTILE TISSUES. 375 



Changes of the medium surrounding muscle as shewn in an analysis 

 of the blood of muscle. 



Analysis of ^ ne g enera l nature of the exchanges between muscle 



the blood and blood has been long known or inferred from the 



flowing to and physical character of the blood flowing out of the muscles, 

 from muscle. r f his blood is defined in general terms as venous ; and 

 ttwgasesb ^ e distinction between arterial and venous blood is one 

 the method of f ^ ne mos t obvious and interesting problems of the 

 Ludwig and physiologist. But it is to Professor Ludwig that we 

 Sczeikow. owe the first accurate examination and account of the 



exchanges. Assisted by Sczeikow 1 , and subsequently by A. Schmidt 2 , 

 he determined by means of the air-pump the composition of the 

 inflowing and outflowing blood of mammalian muscle. The blood 

 was collected from the muscles with as little disturbance to the general 

 circulation as .possible, by the following means. A cannula was inserted 

 into the femoral vein, below the opening of the vena profunda, with its 

 mouth towards the heart, and a loop of ligature was slipped beneath 

 the femoral vein above the opening of the profunda. When the ligature 

 was tightened, the normal current of blood from the profunda into the 

 femoral towards the heart was at once turned from its course and 

 flowed without obstruction through the cannula; when it was slackened 

 again, the current at once resumed its original channel, without the 

 tension having for a moment been raised. In this manner a supply of 

 venous blood from resting muscle was obtained. Arterial blood was at 

 the same time drawn through a cannula in the carotid artery. If it 

 were desired to stimulate the muscles of the leg, electrodes tipped 

 with moistened sponges were applied, one in the inguinal hollow and 

 the other behind the sacrum, opposite the origin of the sciatic 

 plexus. The extraction of the gases was at once undertaken in a 

 Lud wig's blood-pump. As a rule the bloods were examined in the 

 folio wing order: (1) the arterial blood; (2) the venous blood from 

 stimulated muscle ; (3) the venous blood from resting muscles. Very 

 frequently the examination of the last had to be postponed until the 

 following day; sometimes both the second and third kinds were 

 examined on the day after their withdrawal. In this case the blood 

 was kept, surrounded by ice, in the tube into which it had been 

 drawn. 



The analysis of the gases was made by Bunsen's method. 

 On examination it was found that : 



1. The colour of venous blood from active muscle is sometimes 

 brighter and sometimes darker than the colour of venous blood from 



1 Sczeikow, "Zur Lehre von Gasumtausch in verschiedenen Organen :" presented 

 by Prof. Ludwig. Sitzungsber. d. k. Akad. Wien, Vol. XLV. Abth. i. 1862. Second 

 series of experiments. 



2 A. Schmidt, "Das Verhalten der G-ase, welche mit dem Blut durch den reizbaren 

 Sliugethierinuskel stromen." Sitzungsber. der math.-phys. Classe der k. s. Gesellsch. der 

 Wissensch. Vol. xx. p. 12. See also Arbeiten aits der physiol. Anstalt zu Leipzig, 3rd 

 year, 1868 (Leipzig, 1869), p. 1. 



