SEPARATION OF FORM AMD FUNCTION I69 



BECOBD OF EFFECT OF PBOLONGED NAECOSIS 



DISCUSSION: 



There are three major theories regarding the mechanism of narcosis. They are the 

 permeability theory of Lillle and Winterstein; the adsorption theory of Warhurg; and the 

 lipoid theory of Meyer-Overton. According to Henderson (1950) the Meyer's theory is the 

 moat plausible but "No theory of anesthesia' says Henderson "will prove acceptable which 

 is based on a proof of a depression of the resting oxidation of the cell." 



Moog (19^'t-) found a smooth rise in the normal respiration of Rana plpiens eggs from 

 fertilization to the heart-beat stage (#19) and that chloretone, from 0.051^ to 0.09^, had 

 a small but increasing effect on that respiration through late gastrula. The gastrula 

 seemed to be resistent to chloretone. After neunilatlon the effect was more pronounced, 

 weak chloretone effects being reversible, stronger ones producing various permanent ab- 

 normaiitiee, and still stronger ones causing disintegration and cytolysis. On the basis 

 of differential reaction at different stages, Moog postulates two separate chloretone- 

 sensltive respiratory systems, one related to "activity" and the other to "maintenance". 



Karczmar and Koppanyi (V^kT) In brief notes list a large group of anesthetics which 

 were used with larval salamanders. They classify the drugs as to the rapidity with which 

 they bring on Immobilization and from which the larvae recover. The precise mechanism of 

 narcosis has not been determined, and therefore it is unlikely that the action of these 

 various depressants can be directly compared. However, from the point of view of prac- 

 ticality, a reliable, non-toxic, non-injurious anesthetic is necessary for many of the pro- 

 cedures in experimental embryology. Thus far MS 222 has proven to be the most satisfactory 

 of all. It is nevertheless recommended that the student test the value of other depres- 

 sants, particularly chloretone, chloroform, chloral hydrate, ethyl alcohol, and freezing. 



This exercise throws light on the relation of the development of structure in rela- 

 tion to function, since the larvae are immobilized during the development of the muscula- 

 ture. 



