232 DRS. T. L. BRUNTON AND J. T. CASH ON CHEMICAL CONSTITUTION, 
a capacity of about 40 cub. centims. Tubes (a)* for the ingress and egress of the fluids 
are let into the sides of the cylinder, two above and one below. The upper end of the 
cylinder is fitted accurately with a stopper made of cork and vulcanite. The vulcanite 
lid (b) and the cork have an opening in the centre, which can be completely closed by 
means of a brass sliding clamp (c), which is moved by a screw (cl) provided with a 
milled head. This slide-clamp holds securely the femur, if the gastrocnemius of the 
Frog be used; the illium, if the triceps. A binding-screw (e) is attached to the brass 
arm of the clamp, and this receives one of the wires of the secondary coil for direct stimu¬ 
lation. The second connexion with the muscle is effected by means of a Jong and very 
fine coiled wire (f), which is in contact above with another binding-screw situated on 
the vulcanite cap, and below with a trout hook (g) bent into an S shape, on to which 
the wire is whipped. The lower end of the S is connected with the thread or gut 
which passes through the lower end of the cylinder to the lever. A second pair 
of binding-screws on the vulcanite lid are connected with platinum electrodes 
supported on a vulcanite back (h) which projects into the cylinder. These are 
intended for indirect stimulation of the muscle. Finally, the stopper carries a groove 
round the central opening, into which a metal cap (i) fits; application of this cap, 
when the groove has been filled with a drop of oil, renders the upper opening 
practically air-tight. The stopper is of course removed when a preparation for 
examination is placed in the chamber. The lower end of the cylinder is permanently 
closed by a stopper of wood or vulcanite, which is cemented into position. It contains 
two openings: the first, that of a small tube (k), through which a few drops of oil 
may be introduced when it is desired to make the chamber absolutely air-tight, as in 
experiments on the action of gases upon muscle; the second serves for the trans¬ 
mission of the thread or strand of gut which connects the lever and the tendon of the 
muscle. It is made from a piece of thick-walled glass tubing (/) of 1 centim. in length, 
drawn out with an hour-glass contraction in the middle. The calibre at the con¬ 
striction is such that a strand of very fine silk, or the best drawn trout gut just passes 
through it, and no more. When the cylinder is filled with liquid the inner surface of 
this capillary tube becomes moistened, and it is found, whilst all friction is obviated, 
the escape of fluid may be reduced to such an extent that twenty or thirty drops 
only may flow out in the twenty-four hours. We have repeatedly used the chamber 
in experiments extending over twelve hours, and found it practically full at the end 
of the experiment. 
One of the upper openings in the wall of the cylinder is connected, by means of 
a T-tube, with two or more funnels, which contain : (l) the poison or poisons in 
solution to be tested; (2) normal salt solution for washing out the cylinder. The 
tubes connecting these with the cylinder are controlled by clamps. In order to avoid 
escape of current, the fluid in the cylinder is run off before stimulation is applied. 
The nerve can, however, be stimulated whilst the muscle remains in the solution. 
* The letters apply to both diagrams A and B, Plate 10. 
