Effects of Chemical Agents on the Nervous Si/stem. 253 



termine questions many years ago slightly investigated by 

 me relative to the condition of the excito-motor property of 

 the muscular nerves, and of the irritability of the muscular 

 fibre itself, especially in the human subject, and under the in- 

 fluence of various kinds of paralytic affection resulting from 

 the removal of the influence of the cerebrum or of the spinal 

 marrow. I soon found, that the results and phenomena ob- 

 tained, varied with a variety of circumstances, the influence 

 of each of which required to be ascertained before those ques- 

 tions could be determined ; and my attention was soon diverted 

 from my first object, and directed into new channels of in- 

 vestigation. 



But I propose to revert to my first object of inquiry here- 

 after. 



On the present occasion, I confine myself to the subject of 

 the electrogenic condition of the muscular nerves ; that of 

 the incident nerves and of the spinal marrow will form the 

 subject of subsequent papers ; it is one of greater difficulty. 



What hght these experiments throw upon pathology, and 

 upon the modes of action of other physical and chemical agents, 

 as mechanical injury, heat or cold, strychnia or the hydro- 

 cyanic acid, must also remain for future inquiry. 



I cannot introduce my subject better than by a brief sketch 

 of an early experiment ; and I beg, in the first instance, to 

 state, that in all this investigation I have had the able and 

 inval- able assistance of my friend, Mr Henry Smith of Tor- 

 rington Square, whom I cannot sufficiently thank for his 

 untiring attention, as well as generous devotion to this m- 



quiry. 



We took afresh and lively frog (the Rana temporaria, Lin.), 

 and having first divided the spinal marrow near the cranium, 

 to annihilate sensation, and to obviate all idea of the inflic- 

 tion of suffering, and of the interference of volition with the 

 other results, we divided the tissues along the sides of the 

 spinal column, those connecting it with the anterior extremi- 

 ties excepted, and removed all the viscera and the whole of 

 the integuments ; we then removed the bones and muscles of 

 the brachial, lumbar, and pelvic regions.and separated the two 

 femora, leaving the brachial and lumbar nerves perfectly do- 

 VOL. XLV. NO. XC. — OCTOBER 1848. S 



