go 
Scientific Proceedings (43). 
stimulating action and the loss of pigment. Potassium salts 
show a similar stimulating and permeability-increasing action, 
neither of which, however, is checked by the addition of calcium. 
Isotonic LiCl solution shows moderate stimulation with moderate 
loss of pigment; both are checked — as in the case of NaCl — by 
calcium. On the other hand while pure m/2 CsCl produces well- 
marked stimulation and loss of pigment, the addition of calcium 
does not check, but on the contrary markedly accentuates both 
effects. Mixtures of potassium and magnesium chlorides show 
varying action according to the relative proportions of the salts; 
in pure isotonic MgCl 2 solution there is neither stimulation nor 
loss of pigment, but complete reversible muscular anaesthesia; 
the same is true of mixtures containing a decided excess of MgCl 2 
(e. g.j 1 volume m/2 KCl+4 volumes m/2 MgCl 2 ); when the 
proportion of KC1 is increased to one half or more, stimulation 
and with it loss of pigment appear; in mixtures of equal parts 
both effects are slight; in mixtures of 2 vols, m/2 KC1 to 1 vol. m/2 
MgCl 2 both are somewhat increased; in a mixture of 4 vols, m/2 
KC1 to 1 vol. m/2 MgCl 2 there is moderate stimulation with moder- 
ate loss of pigment, though both effects are decidedly less marked 
than in pure m/2 KC1. Saturated solutions of chloroform or 
ether in sea-water produce strong contraction with rapid loss of 
pigment; weak solutions anaesthetize without stimulating or vis- 
ibly increasing permeability. 
II. Experiments with Frog's Muscle. — It was pointed out that 
many cytolytic substances produce slow and usually irreversible 
contraction in vertebrate skeletal muscle; this is the case with soaps, 
bile-salts, various haemolytic alkaloids or glucosides (e. g., saponin, 
digitalin, solanin, agaricin), strong solutions of lipoid solvents 
(chloroform, ether, benzol, toluol, etc.), certain foreign blood sera 
and certain bacterial toxins (e. g., tetanus). The contraction is 
typically slow and steady, unaccompanied by twitching, and passes 
over into permanent rigor. It was found that after treatment of the 
muscle for some minutes with pure isotonic solutions of various 
neutral sodium salts the response to many of the above substances 
is so altered that rapid and vigorous contractions with twitching 
may result. This sensitizing action increases in the order: NaCl, 
NaBr, NaN0 3 , NaC10 3 , NaCNS and Nal, being usually slight 
