38 



ADVANCED LESSONS IN PRACTICAL PHYSIOLOGY 



more power, the long or the short and compact? 

 does the latter possess over the former? 



What advantage 



Annotation. Short compact muscles, such as the gastrocnemius, are meant to 

 lift heavy weights, while long, slender muscles, such as the sartorius, excel in height 

 of contraction rather than in actual force. 



6. Relation of Force to Cross-section. Prepare the other gastroc- 

 nemius muscle of the same animal. Fasten the one already used and 

 this one side by side in the clamp and connect their tendons jointly 

 with the writing lever. Determine the maximal load lifted by them 

 in the manner described previously. Quickly disconnect and arrange 

 these muscles tandem by uniting the tendon of one to the point of at- 

 tachment of the other by means of a short wire. Adjust one wire from 



to 



I 



FIG. 16. SCHEMA TO SHOW THAT 

 CONTRACTING MUSCLE DOES NOT 

 CHANGE ITS VOLUME. 



M, Meniscus of saline solution; 

 S, electrodes through which muscle 

 in receptacle is stimulated. 



FIG. 17. DIFFERENT SYSTEMS OF LEVERS. 

 F, Fulcrum; P, power; W, weight. 



the secondary coil of the inductorium to the body of the upper muscle 

 and the other to the body of the lower muscle. Stimulate with the 

 same strength of current used before, and determine the maximal load 

 lifted by them when arranged in this way instead of side by side. 



7. Effect of Contraction Upon the Volume of the Muscle. Place 

 one of these gastrocnemii muscles in the glass receptacle provided for 

 this purpose. Be sure that its ends are firmly attached to the hooks 

 projecting from the bottom and top of this receptacle. Fill the recepta- 

 cle with boiled saline solution; close it, and adjust the capillary tube so 

 that the "meniscus," indicating the level of the liquid, can be clearly 

 seen. Connect the ends of the hooks with the secondary coil of an 

 inductorium. Stimulate with single induction shocks, and note whether 

 or no a decided change results in the position of the meniscus when the 

 muscle contracts (Fig. 16). 



