« biologica » voi. i. n. 20. 



Prof. R. J. ANDERSON 



Note on chemical stimnli in renard to contraction of inuscles 



It will appear from a survey of papers, or abstracts of 

 papers, that liave appeared lately in journals, or proceedings 

 of societies, that there bave been serious and careful at- 

 terri pts to solve a problem that has occupied the attention 

 of many investigators, viz., the cause, or causes of muscular 

 action. 



The fibres of striated muscle are cemented end to end, are 

 covered with a sheath and supplied witb motor (and sensory) 

 nerves. On being stimulated through the agency of a nerve, 

 or by direct application of the electric current, shortening 

 takes place, and if the impulse be slight and strong enough 

 the muscle has a spasm, and then relaxes again, if the im- 

 pulse be repeated, and the forced stimulus be kept up, the 

 muscle is shortened and thickened. If the stimulation be 

 stopped then the muscle relaxes again. It may even relax 

 owing lo what is called exhaustion. If a chemical irritant be 

 applied to a muscle it may cause the muscle to be perma- 

 nently shortened owing to disorga nisation chicfly, perhaps, 

 and the shrinkage thal lakcs place is Longitudinal, the fibres 

 shrinking exhibil sometimes a well-marked series of undula- 

 tions, where some of the fibres have escaped the irritation. 

 The shrinkage by lliis method may be used to illustrate the 

 ordinary contraction ol* muscle, a weak solution of an acid 

 ie Bometimes sufficienl to cause complete and permanent con- 

 traci ion of 1 be fibres acted on. 



The question arises have the cells in connection wiih 

 muscle tissue anything to do with the formation of a Quid 



