31 8 RALPH S. LILLIE. 



processes, depending as they do on cell-division and growth, 

 are similarly subject to inhibition by anaesthetics. Stockard 

 and McClendon 1 have shown that such substances induce ab- 

 normalities like cyclopia in developing fish eggs, an effect which 

 is to be referred to the arrested development of certain portions 

 of the central nervous system, especially the anterior region of 

 the fore-brain between the optic vesicles. Abnormalities of 

 growth and development as well as of irritability may thus be 

 produced under the influence of anaesthetics. Since an automatic 

 pow r er of growth i. e., increase in specifically organized and 

 metabolically active material is perhaps the most fundamental 

 manifestation of vital activity, the fact that it is subject to 

 reversible arrest by anaesthetic substances is of the greatest 

 biological significance, and illustrates in a striking manner the 

 unity of the conditions which control the most various cell- 

 processes. We may infer that in the general course of con- 

 structive as well as of destructive metabolism, processes are 

 concerned which are identical w r ith those underlying the ordinary 

 manifestations of stimulation. These latter, however, are almost 

 certainly dependent on surface-changes, of which the most 

 essential are probably variations in the electrical polarization 

 of the plasma-membranes (see below, p. 365). The controlling 

 influence of membrane-processes in such fundamental physio- 

 logical activities as growth and assimilation is thus indicated by 

 this susceptibility to arrest by anaesthetics. 



In any complete theoretical discussion of anaesthesia it is 

 necessary first to consider the chief conditions under which 

 living cells in general undergo reversible decrease or loss of 

 irritability. This change occurs under a variety of external 

 conditions, mechanical, thermal, electrical and chemical. Me- 



11 Cf. C. R. Stockard, Archiv f. Entwicklungsmechanik, 1907, Vol. 23, p. 249; 

 Anatomical Record, 1909, Vol. 3, p. 167 ("The Artificial Production of One-eyed 

 Monsters .... by the Use of Chemicals"); Amer. Journ. Anal., 1910, Vol. 10, 

 p. 369 ("The Influence of Alcohol and other Anaesthetics on Embryonic Develop- 

 ment"). Also McClendon ("Physical Chemistry of the Production of One-eyed 

 Monstrosities") in Amer. Journ. Physiol., 1912, Vol. 29, p. 289. Stockard observed 

 the production of these abnoimalities first with magnesium salts, later with lipoid- 

 solvent anaesthetics (alcohol, ether, chloroform, chloretone). Developmental 

 defects are also produced in mammals by alcohol (cf. Stockard, Arch. f. Entwick- 

 lungsmech., 1912, Vol. 35, p. 569; Amer. Naturalist, 1913, Vol. 47, p. 641). 



