No. 2.] 



NER VE-MUSCLE EXPERIMENTS. 



38 



and there held during the prolonged submersions to which 

 Frogs frequently subject their bodies. In the dead Frog the 

 amount of the resistence due to the elasticity of the laryngeal 

 cartilages was found to equal from 0.5 to i. centimeter of 

 water in the manometer used. There is no possibility of 

 muscular action here for the animals were dead in all their 

 parts. A very slight per cent of this amount may be due to 

 the pressure of the mass of the small muscles of the larnyx 

 but this quantity is probably inappreciable. 



A TABLE OF THE RESISTENCE EXERTED BY THE FROG's LARYNX 

 AGAINST PRESSURE FROM WITHIN IN CM. OF MERCURY AND 

 WATER MANOMETERS. 



The resistence in the live frog represents the sum total of 

 involuntary and voluntary efforts of the laryngeal apparatus. 



From what was said concerning the laryngeal muscles it is 

 evident that the dilators are capable of overcoming twice their 

 mass of muscle when they contract, since the two pairs of 

 constrictors are at all times stimulated to the same extent 

 with the dilators. It is also true that the latter are so inserted 

 as to have a decided mechanical advantage over the former and 

 further, that under very strong stimulation they are only 

 capable of producing a slight opening of the glottis at the 

 summit of the glottidean eminence, i.e. at their point of inser- 

 tion, where the action of the constrictors is exerted the least. 

 We meet here the same conditions found in the leg of the 



