210 CARNEGIE INSTITUTION OF WASHINGTON. 



The Chetnistry of Nerve Conduction in Cassiopea, by Alfred G. Mayer. 



In 1914 it was found that if we place ring-shaped strips of subumbrella tissue 

 of the scyphomedusa Cassiopea in sea-water, diluted either with distilled water 

 o^^\'ith 0.415 molecular magnesium chloride, the rate of nerve conduction de- 

 clines in accordance with the formula y = 2 x "-^^j where x is the concentration 

 of the cations sodium, potassium, and calcium in the diluted sea- water, that 

 in normal sea-water being 100; and y is the relative rate of nerve conduction 

 in the same diluted sea-water, that in normal sea-water being 100. This for- 

 mula resembles the well-known one for chemical adsorption, and suggests that 

 negatively charged colloidal elements of the nerve may attract the sodium, 

 potassium, and calcium cations to their smiaces, and that these adsorbed 

 cations conduct the nerve impulse. 



The exponent 0.86 is higher than in the usual adsorption formulae, this being 

 due to the H ion of H2CO3 present in the distilled water used in diluting the 

 sea-water; the H ion in weak concentration is well known to be a powerful 

 stimulant, while in greater excess it is a depressant. 



This season (1915) these experiments were repeated, the sea-water being 

 diluted, however, with distilled water which was so far as possible freed from 

 carbon dioxide by having bubbled through it air which had passed through a 

 soda-lime tube, after which the water was rendered slightly alkaUne by adding 

 1/10000 molecular NaOH. This showed that in common with the H ion, the 

 OH ion is also a stimulant for the rate of nerve conduction in weak concentra- 

 tion, and a depressant in stronger concentration. It is necessary, therefore, 

 to make use of neutral distilled water in order to determine the true effects of 

 the sodium, calcium, and potassium cations. In the purest distilled water 

 obtained in 1915, which, however, contained some free OH ions, the formula 

 for the rate of nerve conduction was y = 2.512x'^-^. 



It seems possible, therefore, that the nerve stimulus may be conducted by 

 adsorbed cations of sodium, calcium, and potassium, but this rate of nerve 

 conduction is accelerated by any OH or H ions which may be present. 



W. M. Bayliss, 1915 (Principles of General Physiology, p. 61), states that 

 heat dissociates an adsorption compound. This, together with the onset of 

 asphyxiation at high temperatures, may account for the fact shown by Harvey, 

 that the rate of nerve conduction in Cassiopea rises more slowly with rise in 

 temperature than one would expect were it a simple chemical reaction; the 

 OH ions tending to follow the van't Hoff exponential equation for chemical 

 activity with rise in temperature, while the adsorbed Na, Ca, and K, being 

 reduced in concentration, tend to lower the rate, which is still further lowered 

 above 33° C. by the development of heat asphyxiation. These suggestions 

 are presented merely as a possible explanation of the phenomenon of nerve 

 conduction. 



The Solution of Limestone in Sea-Water, by Alfred G. Mayer. 



Thin pieces cut from a compact shell of the mollusk Cassis, having a spe- 

 cific gravity of 2,88 and ranging in superficial area from 57.6 to 85 sq. cm., 

 were used in these experiments. Two glass carboys were sterilized by washing 

 them successively with HCl, KOH, alcohol, and distilled water, and one of 

 these was filled with 45 liters of sea-water which had been doubly filtered 

 and then heated within the carboy to 72.5° C, thus sterilizing it. The other 

 carboy was filled with the same volume of sea-water taken directly from the 

 ocean and neither filtered nor sterilized. Also, two 15-liter glass vessels were 

 inclosed in black, light-tight wooden boxes, so as to form dark chambers to 

 prevent plants from growing within them, and were so arranged that if placed 



