ii SENSIBILITY OF THE INTEKNAL OKGANS 65 



According to Lennander, the same holds for the thoracic and 

 cranial cavities. The lungs and visceral pleura are insensitive, 

 and the pains felt in the chest in certain illnesses are caused by 

 the transmission of excitations to the parietal pleura, which is 

 sensitive under normal conditions also. 



The brain is insensitive, and the pains in the head so frequently 

 felt are due to transmission of excitation to the dura mater. 



Generally speaking, Lennander holds it probable that all the 

 organs innervated by the sympathetic alone, and by the branches 

 of the vagus after the separation of the recurrent nerve, are 

 insensitive to pain, not merely in the healthy but also in the 

 inflammatory state. 



This statement does not seem to be justifiable, at any rate not 

 in such a general form. How can we deny the sensitiveness to 

 pain of the bile duct, the ureter, and the intestinal tract in cases 

 of gall stones, of hernia, and of other forms of obstruction of the 

 digestive canal ? On the other hand, the work which Ducceschi 

 carried out in our laboratory " On the nerves of the stomach " 

 (1905) shows clearly that mechanical, thermal, and electrical 

 stimuli applied to the outer surface of the stomach of normal 

 dogs and cats cause obviously painful reactions (general agitation, 

 disturbed respiration, cries, characteristic movements of the tail, 

 similar to those made by the cat when it is hurt by stimulation 

 of the cutaneous sensory nerves). The reactions are seen even 

 after section of both vagi, or both splanchnics ; they only cease 

 when both have been cut. " It is interesting," writes Ducceschi, 

 " to note that the stomach in certain cases seems to become more 

 sensitive in proportion to the time that has elapsed since its 

 exposure. Simultaneously with the increase of sensibility in the 

 stomach, cutaneous sensibility declines. At the end of the experi- 

 ment, after about two hours, a slight tap on the wall of the stomach 

 causes strong general reactions, while pinching the ear, paw, or 

 the skin of the abdomen does not cause even the slightest reaction. 

 There is evidently shock of the peripheral sensory apparatus, 

 accompanied by gastric hyperaesthesia." 



From Lennander's latest communications it appears probable 

 that the mucous membrane not only of the rectum, vagina, and 

 uterus, but also of the ovary, oviduct, and ligamenta lata are 

 insensitive to pain. All these parts can, he says, be operated on 

 without pain to the patient, provided there is no traction of the 

 connective tissue by which they are united to the walls of the 

 pelvis and the parietal peritoneum. Probably the testicles and 

 epididymis too contain no nerves of pain, though the parietal fold 

 of the tunica vaginalis is highly sensitive. We must reserve our 

 opinion on these theories also. 



In opposition to and parallel with the clinical observations of 

 Lennander, the clinical theory of referred pain has recently 



VOL. IV F 



