The Metiibulisui of Voluntary Muscle 225 



oozinsr of blood from the cut surface of the muscles was arrested and loss 

 of heat at the same time prevented. 



The muscles after removal were rapidly cleaned of fat and adherent 

 connective tissue, care bein<; taken to prevent loss of moisture by keep- 

 ing them in a capsule placed under a bell-jar the roof of which was lined 

 by a layer of moistened tilter-paper. The nniscles were then rapidly 

 minced, mixed thorou<;hly, and samples weighed on a delicate balance 

 for the difierent analyses. 



Determinations were made of the content of water, of creatine, creati- 

 nine, total nitrogen, and of ash. The samples to be dried were placed under 

 alcohol over niirht, then dried for several hours in a steam-lieated oven at 

 97° C. Afterwards they were dried to a constant weight at 105 C. In the 

 case of those used for determination of the ash, incineration followed drying 

 in the steam oven. Creatine and creatinine were determined by Folin's 

 recent method, usincr as standard a solution of creatinine zinc chloride 

 recently prepared. The sample of muscle used for creatine was also 

 employed for total nitrogen determination. After boiling in the auto- 

 clave, the contents of the flask were filtered through a small plug of 

 glass-wool into a 200-c.c. flask. The extracted flesh and glass-wool 

 were then flnely ground up in a mortar and added to the contents of 

 the flask. After flllincr to the mark, the flask was then shaken up 

 thoi'oughly. In this way a uniform suspension of extracted muscle in 

 the acid liquid was obtained which could be accurately measured by 

 a pipette. After each sample was measured off", the mixture was again 

 shaken up before another was taken. The procedure proved satisfactory, 

 a,nd gave remarkably concordant results in the duplicate analyses 

 carried out. 



In makincT the creatine determinations, Folin's directions were followed 

 almost exactly. Particular care was taken in adding the 10 per cent. 

 NaOH solution both for neutralisation and for development of the colour. 

 In all cases this was done by counting the number of drops required, and 

 not simply by measurement from a burette. Further, the readings were 

 made in groups of four, two from each limb. Thus the muscle extracts 

 from the two sides were tested against the same standard solution. 

 Possible errors from slight variations in the standard (if made up at 

 diff"erent times for the two sides) were thus avoided. 



The experiments performed fall into two groups: first, a series in 

 which the left anterior crural and sciatic nerves were excited, the blood 

 supply of the limb being maintained without interference ; and second, a 

 series in which the same nerves were excited, but in addition the chief 

 artery of the limb was ligatured. This latter was done under the 

 impression that possibly some of the products of excitation might remain 

 in the muscles and escape being washed away or otherwise removed, as no 

 doubt happens when the stream of blood through them is unaltered. The 

 results, however, did not conform with these anticipations. 



