Meinbrcuie Formation 373 



1 Short exposures to high temperatures. 



2 Long exposures to low temperatures. 2* 



5 Electrical shocks. 



1 Charging eggs (Strongylocentrotus) Delage. 



2 Induced shocks (Arbacia) McClendon. 



3 Constant current (.Asterias) {:) Shucking. 



6 Chemical reagents. 



1 Specific actions— K, Mg; Mn Ni and Co. (?) (Delage) 



2 Alkaloids and glycosides (saponin, solanin, pilocarpin, strychnin, 



quinin, hyocyaniin, nicotin.) 



3 Tannin and reared substances. 



4 Fat solvents (ether, chloroform, benzol, alcohol). 



5 Bile salts (Na taurocholate and glycocholate). 



6 Blood sera (of rabbit, pig, ox, and certain worms). 



7 Acids and alkalies. 



7 Absence of oxygen (weak CNK and ()-free sea-water). ^6 



A glance at the above classification will show the general 

 similarity in the means of stimulating muscles and sensitive plans 

 and of exciting unfertilized eggs to develop. They are both 

 stimulus responses, and may be expected to show a common 

 underlying cause conditioning the response. I have discussed 

 this in a preliminary note in Science^^ and quote from it: "A con- 

 siderable mass of evidence now exists, especially emphasized in 

 recent papers of Ralph Lillie,^^ that stimulation of muscles is 

 effected by a momentary increase in the permeability of the 

 muscle membrane to CO. allowing its more ready escape during 

 contraction. CO2 is the chief end product of the energy-yield- 

 ing reaction on which contraction depends and its removal from 

 the cell allows the reaction to proceed (during contraction) to a 

 new equilibrium (of rest) when checked by a second accumulation 



-"' .'\bsence of oxygen and low temperature as well as hypertonic solutions (in part) seem to act as 

 correcting agents, setting the oxidations in the egg on the right path to proper development, (Loeb), 

 and as such do not come for discussion witliin the scope of this paper. 



2' Science, n. s., XXX, p. 694, 1909. 



-'Lillie, R. S.: Am. Journ. Phvsiol., xxii, p. 75, 1908; xxiv, p. 14, 1909; and xxiv, p. 459, 1909. 



