TRANSACTIONS OP THE SECTIONS. 167 



difference as regards fundamental characters ; the fibres, granules, cells, and con- 

 nective tissue found in the one are found in the other : nothing is found in the one 

 that is not in the other: they are identical. Our conclusion, therefore, must be 

 that they are identical in property. If sensibility be the property of any ganglionic 

 mass, it must be the property of all. Numberless experiments have shown the author 

 that every ganglionic centre in a vertebrate or invertebrate animal is the seat of sen- 

 sibility. Physiologists declare the phenomena to be due to reflex action, not to 

 sensibility ; but this the author considered to be only one among the many equivoques 

 which arise in the absence of a scientific nomenclature. 



Whatever the peculiar force developed in the centres may be, it assuredly is not 

 the same as that developed in the nerves. Nerve-fibre has one property, the nerve- 

 cell another. It is proposed to call the one neurility, and the other sensibility. By 

 neurility is meant the property of the living nerve-fibre, which excites sensation in a 

 centre, contraction in a muscle, and secretion in a gland. By sensibility is meant 

 the property of the living nerve-cell, as contractility is the property of the muscular 

 fibre. 



By recognizing the simple fact that all nerve-centres whatever, no matter how 

 various their functions, have one common property, such as sensibility, we shall be 

 able to find our way through many obscurities of nervous physiology, and shall 

 Understand how the spinal cord of vertebrata, or separate ganglia of invertebrata, 

 can separately manifest sensation and volition — as experiment proves— we shall 

 understand why an animal like the Amphioxus, which has no brain at all, is capable 

 of sensation and volition, though not of what we call thinking ; and, finally, we shall 

 understand why all animals, in spite of the great diversities in their nervous systems, 

 have one fundamental character in common, and that is sensibility. 



The author concluded by proposing that the British Association should appoint 

 a committee of physiologists to draw up a Report, and to lay the basis of a new 

 nomenclature. From the illumination of many minds a reform might issue, and a 

 new era be inaugurated. __. 



A Demonstration of the Muscular Sense. By G. H. Lewes. 



Physiologists are generally agreed as to the existence of a special class of sensa- 

 tions arising from the exercise of the muscles and regulating their adjustments ; but 

 there are still disputes as to whether these have their origin in the muscles them- 

 selves, or in the skin. The following experiments were made by the author to 

 determine whether the stretchings and foldings of the skin were or were not the 

 source of these sensations. 



A frog was completely skinned, with the exception of a small patch around the 

 anus, and another patch over the eyes and nose. On all the parts from which the 

 skin had been removed, there was absolute insensibility to all external stimuli : 

 pricking, pinching, cutting, cauterizing, and burning were all unable to elicit the 

 slightest trace of sensibility. A leg was cut off bit by bit, without the frog's once 

 moving ; but in the two spots which still retained their skin, sensibility was easily 

 excited. A touch or a prick made the frog hop away, draw up its leg, or defend 

 itself. 



If this frog were placed on its back, it immediately turned round again, and settled 

 its legs comfortably. If the hind legs were pulled abruptly down, they were quickly 

 drawn up again ; but if they were pulled gently down, they remained where placed — 

 until a few minutes had produced a feeling of fatigue in the stretched muscles, and 

 then the leg was withdrawn. Had not the frog felt this position uncomfortable, 

 there would have been no reason for altering it. The proof of this was seen by 

 varying the position : in proportion as the position was unusual, it was maintained 

 for a shorter period. To these evidences of muscular sensibility may be added the 

 leaping, and the complicated actions of self-defence when irritated, none of which 

 could be effected without nice muscular adjustment. 



The frog, therefore, which has been rendered totally insensible to external impres- 

 sions, by removal of its skin, is still seen to manifest all those phenomena usually 

 attributed to the muscular sense. A question arises, whether these phenomena are 

 due to any feelings originating in the muscles, or are solely due to the will of the 



