No. 2.] NERVE-MUSCLE EXPERIMENTS. 38 1 



is obtained whether one varies the intensity of stimulation 

 while using a given maximum rate, or varies the rate while 

 using a given maximum intensity. It is obvious that Fick and 

 Bour's explanation is inadequate, for if no other elements than 

 the length and size of nerves and muscles, or differences in their 

 position, entered into the problem, the stronger group of 

 muscles would ultimately overpower the weaker with any 

 strength of the stimulus. Differing irritabilities is a "blanket" 

 explanation, and may be said to include the third explanation 

 which attributes these results to differences in the rates of 

 stimulation required by the two sets of muscles. The latter 

 explanation presents the matter in a specific manner, so that 

 we should be able to determine by experiment whether it is 

 a causa vera or not. 



The apparatus used consisted of a Du Bois Reymond in- 

 duction apparatus for controlling the intensity of the Faradic 

 current, a Bowditch interruptor for controlling the rate of 

 stimulation. 



The Frogs were prepared by destroying both the brain and 

 spinal cord and dissecting out the laryngeal nerve, or the 

 sciatic nerve, as the experiment required. In a part of the 

 experiments shielded electrodes were placed on the nerve, from 

 one to one and a half centimeters from the larynx, and in 

 another set simple hook electrodes were used to hook up the 

 nerve at any point of its course. 



To determine whether or not a closure of the glottis was 

 called forth by stimulating the laryngeal nerve, a delicate 

 celluloid paper spring was placed in the ritna glottidis so as to 

 slightly open the laryngeal passage. 



The larynx of Rana is composed of three 1 cartilaginous 

 plates formed into a complicated mechanism, the parts of 

 which I will not here describe. The ground plan is simple 

 enough and consists of a basal ring formed by the cricoid car- 

 tilage which has an equatorial loop projecting ventrad. This 

 loop is so placed relative to certain processes of the ring that 

 the roots of the lungs, which are attatched to it (a trachea 



1 The thyroid cartilage is absent, but the posterior comua of the hyoid 

 assumes its functions. 



