ABSTRACT
In studies of the activity of isolated organs it is desirable to bathe them in a fluid similar to that found in the intact animal. Previous work on nervous systems indicates that their electrical activity is greatly affected by the concentration of ions in the medium, except in cases where they are enclosed in a thick impermeable sheath. In gastropods the suitability of a 0·6-0·75 Locke solution for in vitro experiments on isolated organs was demonstrated by Cardot (1921), who studied the effect of different dilutions of mammalian Locke solution on the frequency and amplitude of the heart beat in Helix. A 0·7 dilution (sometimes called Cardot’s solution) has generally been used by previous workers on the nervous system of gastropods, and their preparations retained constant electrical activity for many hours, but there is an absence of studies on the effect of variations in the composition of the bathing fluid on the gastropod nervous system. This is of interest because the blood of slugs and snails is known to show considerable fluctuations in concentration. The problem may also be of significance in relation to the general behaviour of the animal, since it is known that these fluctuations are related to the activity of the animals.
