30 CEREBRAL FORCES. [i. 



place sideways on an undivided nerve, that is to say, neither at 

 its origin nor termination, but on the trunk between these two 

 points, if it be propagated, it can pass onwards from the point 

 of impression (not from its termination !) upwards to the brain, 

 and in like manner from the same point, (and not from the 

 cerebral origin of the nerve !) downwards to the terminating 

 fibrils. When by a touch or some movement communicated to 

 it, or by any other agency whatever, an animal machine (and 

 consequently a nerve) is so changed that it produces actions, 

 which cannot be satisfactorily explained by the physical and 

 mechanical laws of motion, or in other words, so that it mani- 

 fests animal actions (6) ; the change thus excited in it is termed 

 a sense-like [sinnlich] impression {nerve-feeling). A sense-like 

 impression made on the cerebral origin of a nerve in a direction 

 downwards, or on its trunk, if propagated, passes outwards to- 

 wards the terminating fibrils of the nerve ; on the contrary, a 

 sense-like impression made on the terminating fibrils of a nerve, 

 or on its trunk, in a direction upwards from the termination to 

 the brain, if propagated, is transmitted in that direction.^ 



» The indefinite use of the words " sinnlich," " sensible" " sentient," and " sensa- 

 tional," by German, French, and English writers, on the physiology of the nervous 

 system, has led to innumerable misconceptions by both authors and readers. Agents 

 frequently change the condition of the nervous system, and excite it to action with- 

 out being felt : that is to say, without exciting pleasure or pain, or the feeling of 

 self-consciousness, or any perception whatever of the agent or agents, or of the re- 

 sults of their action ; yet movements result therefrom as much adapted to attain a 

 definite and designed end, as if the agents were felt, and the mind itself acted. In 

 the text, Unzer analyses these phenomena, and terms the change which takes place 

 in a nerve, when agents so act upon it, a sinnlich impression or Nervengefuhl — 

 nerve-feeling. It is obvious from the context, that to render sinnlich by sensational 

 or sentient would give an erroneous idea of the author's meaning, if by those words 

 we mean " of or belonging to sensation or perception ;" for he emphatically dis- 

 criminates, in a subsequent paragraph (34), and elsewhere, between the property of 

 mere respondence to impressions seated in the nerves (** nerve-feeling"), and the 

 property of sensation or perception requiring a special organ, — a cerebrum. 



There is no English word which corresponds to sinnlich as thus used by Unzer, 

 which I have hitherto rendered by sense-like. The term sinnlicher Eindruck may 

 be very correctly rendered, however, by the word '* impression," as used by modern 

 neurologists ; for when we say that light makes no impression on the nerves of the 

 skin, we mean to say that it excites no change in their medulla, so that appropriate 

 vital movements shall follow. I therefore propose to use the word "impression" 

 simply, as conveying the meaning of sinnlicher EindrucA, deducing therefrom the 

 adjective impressional. 



It is to be observed, however, that sinnlich is used by Unzer in other senses, 

 when it may be rendered by sentient or sensational. When sinnlich impressions 



