ADDITIONAL SENSES. 297 



only be esteemed a peculiar variety of tact in the mucous membrane 

 of the genital organs, differing from ordinary tact in those parts, in 

 requiring in both sexes a special condition of the membrane; and, in the 

 male, one such, that the sperm, when excreted, shall make the neces- 

 sary impression upon it; and, consequently, appertaining to both the 

 external and internal sensations ; the state of the membrane being 

 referable to the latter, and the effect of the contact of the sperm to the 

 former. Some have spoken of a sense of heat and cold: this has been 

 referred to under the head of tact; others of a muscular sense, by 

 which we acquire a knowledge of the motions that muscular' contractions 

 give rise to, and learn to apportion the effort to the degree of effect to 

 be produced. Animal magnetizers have suggested a sixth sense, to which 

 man owes the capability of being acted upon by them: but this is suppo- 

 sititious, and the facts admit of a more ready and satisfactory explana- 

 tion. A sense of hunger has been described as situate at the upper 

 orifice of the stomach : a sense of thirst in the oesophagus, and a pneu- 

 matic sense in the lungs ; but these are rather internal sensations. 



The German physiologists have suggested another sense, which they 

 term coenaesthesis, Gemeingef Uhl, Gemeinsinn, JKorpergefuhl, 

 Lebenssinn, Individualitatssinn, and Selbstgefiihl ("common 

 feeling, common sensation, bodily feeling, feeling of life, sense of life, 

 sense of individuality, and self-feeling"). This is not seated in any 

 particular part of the body, but over the whole system; hence termed 

 "common." It is indicated by the lightness and buoyancy, which we 

 occasionally experience, apparently without any adequate cause; as well 

 as by a sense of lassitude and fatigue unconnected with muscular action 

 or disease. To it, likewise, belong the involuntary shuddering, glow, 

 and chilliness, experienced under like circumstances. It is manifestly 

 one of the numerous internal sensations, felt by the frame, and every 

 portion of it, according as they are in a perfect state of health, or 

 labouring under irritation or oppression; but can scarcely be regarded 

 as an additional or sixth sense. 1 



It has been supposed, that certain animals may possess other senses 

 than the five. Of this we can have no positive evidence. We are 

 devoid of the means of judging of their sensations ; and if we meet 

 with an additional organ, which seems adapted for such a purpose, we 

 have nothing but conjecture to guide us. Under the sense of touch it 

 was said, that the bat is found to be capable of avoiding obstacles 

 placed in its way intentionally, when the eyes, nostrils, &c., have been 

 closed up ; and that it readily returns to the holes in caverns to which 

 it is habituated. Spallanzani supposed that this was owing to its being 

 possessed of a sixth sense. We have seen, that the circumstance is 

 explicable by unusual delicacy of one of the external senses. 



Again ; the accuracy with which migratory animals return to their 

 accustomed haunts, has given rise to the notion of a sense of locality. 



Quadrupeds, the ape not excepted, have two bones in the face, in 



1 Purkinje, art. Ccensesthesis, in Encycl. Worterb. der Medicinisch. Wissenschaft. viii. 116, 

 Berlin, 1832; and Miiller's Elements of Physiology, by Baly, P. v. p. 1087, London, 1839. 

 See, also, E. H. Weber, art. Tastsinn und das Gemeingefuhl, in Wagner's Handworterbuoh 

 der Physiologic, 22ste Lieferung, s. 562, Braunschweig, 1849. 



