168 SEPARATION OF FORM AND FUNCTION 



Upon returning the embryos from prolonged narcosis to normal medium, determine the 

 speed of recovery of response but more particularly compare the stage of development 

 with that of the controls. Note any morphological and behavior variations when compared 

 with the untreated controls. Have the muscles developed normally in spite of total anes- 

 thesia? 



DISCUSSION: 



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

 permeability theory of Lillie and Winterstein; the adsorption theory of Warburg; and the 

 lipoid theory of Meyer-Overton. According to Henderson (1930) the Meyer's theory is 

 the most 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 (I944) found a smooth rise in the normal respiration of Rana pipiens eggs from fer- 

 tilization to the heart-beat stage (#19) and that chloretone, from 0. 03% to 0. 09%, had a 

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

 to be resistent to chloretone. After neurulation the effect was more pronounced, weak 

 chloretone effects being reversible, stronger ones producing various permanent abnor- 

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

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

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



Karczmar and Koppanyi (1947) 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 satis- 

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

 depressants, particularly chloretone, chloroform, chloral hydrate, ethyl alcohol, and 

 freezing. 



This exercise throws light on the relation of the development of structure in relation to 

 function, since the larvae are immobilized during the development of the musculature. 



REFERENCES 



ANDERSON, B. G. C G. J. JACOBS - "The apparent thresholds of narcosis and toxicity for some normal aliphatic alcohols and 

 their isomers. " Anat. Rec. 99: suppl. 43. 



BANCROFT, W. D. G G. H. ROCHTER, 1931 - "The chemistry of anesthesia. " Jour. Phys. Chem. 33:215. 



CLARK, A. J., 1937 - "The action of narcotics on enzymes and cells. " Trans. Faraday Sic. 33:1057. 



FISHER, K. C, 1942 - "Narcosis." Canadian Med. Ass'n. Jour. 47:414. 



FOX, D. L. , 193i - "Carbon dioxide narcosis. " Jour. Cell. Comp. Physiol. 5:75. 



GREIG, M. E. , 1946 - "The site of action of narcotics on brain metabolism. !' Jour. Pharm. Exp. Therap. 87:185. 



HENDERSON, V. E. , 1930 - "The present status of the theories of narcosis. " Physiol. Rev. 10:171. 



HILLER, ST., 1924 - "Influence de I'alcool ethylique sur le developpement de Rana fusca." Bull, de I'Acad. Polonaise des 

 Sc. ct des Lettres. B. 623. 



JOHNSON, F. A., D. BROWN, D A. MARSLAND, 1942 - "A basic mechanism in the biological effects of temperature, pres- 

 sure, and narcotics. " Science. 95:200. 



JOWETT, M. , 1938 - "The action of narcotics on broin respiration. " Jour. Physiol. 92:322. 



KARCZMAR, A. G. C T. KOPPANYI, 1947 - "The effect of stimulant drugs on overt behavior. " Anat. Rec. 99: suppl. 64. 



KOPPANYI, T. CA. G. KARCZMAR, 1947 - "The effect of depressant drugs on overt behavior. " Anat. Rec. 99: suppl. 64. 



MATHEWS, S. A. C S. R. DETWILER, 1926 - "The reactions of Amblystoma embryos following prolonged treatment with 

 chloretone." Jour. Exp. Zool. 45:279. 



McELROY, W. D. , 1947 - "The mechanism of inhibition of cellular activity by narcotics. " Quart. Rev. Biol. 22:25. 



