198 Mr H. F. Baxter on Muscular Power. 
In my preliminary experiments I first took the weight 
of the frog, but soon found that during its preparation it 
frequently ejected a quantity of fluid, amounting to 10 or 
15 grains, or more ; in subsequent experiments it was pre- 
pared in the following manner:—The tendo-Achillis was 
exposed by removing a portion of skin ; a piece of strong 
silk was then passed beneath it by means of a needle, and 
tied on to the tendon, so as to form a loop to which the 
hook connected with the pulley could be attached. A por- 
tion of skin of the thigh, over the course of the sciatic 
nerve, was removed, and the ligatures tied on to the fore- 
extremities, and to the hind limb. ‘The animal was then 
secured in a screw of paper and weighed ; the weight of the 
strings and paper were subsequently deducted from the total 
weight. The sciatic nerve was then exposed and divided, 
and the frog fastened on to the apparatus. 
To excite the nerve, and in order to have a constant 
power, not possessing a rheostat, one of Smee’s middling 
sized cells, with amalgamated zinc plates, was used. The 
acid employed consisted of dilute nitro-sulphuric acid (1 acid 
40 water). A thick copper wire was connected with the 
platinode, the free extremity of which passed through a 
piece of cork and was bent at right angles to the extent 
of half an inch, so as to press down upon its surface ; be- 
tween the cork and the wire was a piece of coarse bibulous 
paper, and which was folded over the extremity of the wire; 
the paper was kept moistened, and upon it the nerve rested. 
The wire connected with the zincode was not so thick, 
and its central portion wound round in the form of a helix, 
by the elasticity thus given to it its extremity could be 
readily applied to the tendo-Achillis without moving the 
cell, and facilitated the making and breaking of contact. 
The current was always used as the direct form, @.e., it tra- — 
versed the nerve and muscle to the tendo-Achillis. 
The precautions to be observed are numerous. | 
1. Avoid the loss of Blood. UHaving carefully laid bare 
the sciatic nerve in the upper part of the thigh with a blunt 
pointed probe, it was withdrawn and divided; but instead 
of exposing the nerve throughout its whole course by sepa- 
rating the muscles, it was again carefully dissected out at 
