130 REPORTS ON THE STATE OF SCIENCE.—1918. 
on account of electrostatic forces. We shall see presently that this 
fact plays an important part in the electrical behaviour of living 
cells. 5 
The action of anaesthetics is of interest. Osterhout (1916) has 
shown that there are two stages in this action, of opposite nature. 
The first one is a decrease in permeability, the second an increase. 
The former is recovered from on removal of the anesthetic, while the 
latter is a toxic effect, irreversible and leading to death. Remember- 
ing that the characteristic action of anesthetics is to make a cell 
unable to enter into a state of excitation, and that the state of ex- 
citation is associated with an increase of permeability, we see that 
the first stage is the real anesthetic action. Whether the state of 
excitation is a consequence of the permeability change, or vice versa, 
is not certain, but it may well be that the preventicn of the per- 
meability change also removes the possibility of excitation. The 
pronounced “lipoid-solubility ” of the volatile anesthetics suggests 
that their action is on the lipoid constituents of the membrane, but 
magnesium salts have a similar action, so that it seems probable that 
the relationship to lipoids may be merely incidental. 
The interesting observations of Meigs (1915) on the permeability 
of membranes of colloidal calcium and magnesium phosphates show 
that such membranes may be impermeable to sugar, phosphates, &c., 
but highly permeable to ethyl alcohol. Hence this latter property is 
not limited to “lipoid’’ membranes. 
As pointed out previously, calcium salts decrease, while sodium 
salts increase the permeability of the cell-membrane, so that the effects 
may be balanged. Anesthetics also decrease the permeability. 
Hence they should oppose the effect of sodium salts. This has been’ 
shown by Lillie (1914) to be the case. 
Since the membrane is a local concentration of components of 
the protoplasm of the cell, there must always be an equilibrium 
between the two. Hence a change in either involves a change in 
both. It is not a matter of surprise, therefore, to find that substances 
applied to the outside of a cell may effect marked changes in its 
chemical behaviour, even when they are unable to pass through the 
membrane. Thus, as mentioned above, sodium hydroxide does not 
enter the living cell, but it increases greatly the rate of its oxidation 
processes. Newton Harvey (1914, p. 142) finds that although weak 
alkalies (ammonia and amines) enter muscle cells almost instantly, 
as shown by the change in colour of neutral red within the cells, 
their contraction does not cease until some time later. Strong 
alkalies (sodium hydroxide) abolish contractile power at once, but 
do not enter the cell until long afterwards. The effect of electrolytes 
on the beat of the heart and on muscular contraction in general is - 
on the cell membrane (see Straub, 1912, p. 14, and Overton, 1904, 
p. 202). A somewhat remarkable phenomenon occurs in the case 
of such drugs as muscarine and pilocarpine, which produce their 
effects while passing through the membrane in either direction, 
whether entering or leaving the cell.. When in equal concentration 
on both sides their effect is nil (Straub, 1907, Neukirch, 1912). 
In order that the cells of the tissues of the higher animals shall 
maintain their normal water content and volume, it is necessary that 
