PAIN IN VISCERA. 993 



sensory nerve-endings. It has been urged that a change, e.g. a diminution 

 in the volume of the circulating blood, may be perceptible by means of the 

 heart nerves. 1 Deficiency of lymph might certainly induce a relaxation 

 of many membranes to which afferent nerve fibres are distributed, e.g. capsules 

 of Pacini corpuscles, etc. Such changes may be thought too weak to produce 

 effect ; yet a character of common sensation is a pre-eminent tendency of the 

 impressions building it to fuse, to summate, to cumulate. This is as unmis- 

 takable in pain, as in tickling, the sexual "feeling," etc. This explains why 

 mere excessive duration of a stimulus which at the outset lies far below the limen 

 for pain, may bring it up beyond that limen and make it effective, even 

 insufferable, e.g. a tight boot or hat. Hence it is impossible to deny that 

 visceral stimuli, that for a short time are of negligible intensity, may, if con- 

 tinued, develop potency for sensation. 



From the above it is evident that the nature of the condition of the body 

 which is the source of the feeling of hunger, is not definitely known, nor is the 

 manner in which the condition can react on sense. Nevertheless, the kind of 

 condition which excites the " feeling " is clear enough. It is a condition in 

 which requisite supply of material for maintaining normal life is withheld, in 

 which injury is threatened, and to which the dativus incommodi of the gram- 

 marians is applicable. A need arises like the besoin de respirer, and becomes irre- 

 pressible, i.e. excites to action. Hunger eventually becomes painful, even more 

 than, conversely, satiety is pleasant. The dogs from which the cerebral hemi- 

 spheres had been removed by Goltz became restless as feeding-time drew near. 

 This restlessness subsided when the usual quantity of food had been taken, 

 and the dogs then invariably " refused " further quantities of food. In other 

 words, the restlessness was part of the hunger reflex, and so far, like the 

 movements of " swallowing " brought out by food placed in contact with the 

 dog's muzzle, could only be excited in the hungry state. So also the male 

 pigeon, after removal of the hemispheres, will in spring coo all day long, and 

 show distinct signs of sexual excitement. But his activity is entirely in- 

 different toward the hen-bird placed near ; he leaves her unnoticed. The 

 muscular restlessness (the motor adjunct of the " hunt " for food) stands 

 evidently in the same relation to this visceral sensation of painful " tone " as 

 does the flexion of the hip and knee (withdrawal of the foot) in relation to 

 the cutaneous sensation of painful "tone" initiated by a pinch of the foot. 



The use of the discussing of the feeling of hunger to the argument here 

 is, that it broadly indicates how the production of painful sensations by 

 the same visceral afferent nerves as those ordinarily employed in 

 unpainful and in even unconscious neural reflex reactions, comes about. 

 That in some instances the visceral pain is due to tension, forms, to my 

 thinking, not a difficulty, but merely indicates that the normal adequate 

 stimulus is of a mechanical kind.- 



A further difficulty for supposing that the viscera are provided with 

 specific nervous apparatus for a " pain-sense," is the following : — 



" It may happen to a man to suffer pain in a particular region or 

 tissue of the body once only in the course of his lifetime, or possibly not 

 even once ; nay, we may suppose that in this or that region or tissue 

 pain is felt once only in one individual among a large number of 

 persons." 3 How, if this pain requires, to carry it out, a special 

 mechanism, including special. afferent nerve fibres, can, in the case in 



1 Budge, Nora acta phys.-med. Acad. nut. curios, 1860, tomo xxvii. ; " Physiologie," 

 Leipzig, 1862, S. 815. 



2 See C. A. Strong, Psychol. Rev., N. Y. and London, 1896, vol. iii. p. 64, contra 

 H. R. Marshall, ibid., 1895, vol. ii. p. 594. Of. also E. H. Weber, Wagner's " Hand- 

 worterbuch," Bd. iii. (2) S. 580. 



3 M. Foster, "Text-Book of Physiology," London, 1900, part iv. 



VOL. II. — 63 



