ON THE ORGANIC FUNCTIONS. 873 



especially, are more tolerant of irritation and injury ; and such cases as those 

 recorded by Dr. Carnochan and Dr. Conner, 1 where Meckel's ganglion was 

 extirpated, and no apparent mischief followed, show that some other condi- 

 tions than the mere abolition of the function of the sympathetic ganglia 

 must be present in order that impairment of nutrition may take place. 



720. It is to be observed, moreover, that whilst some of the phenomena 

 above alluded to are inexplicable on the supposition that the blood supply 

 is interfered with, possibly by persistent contraction of the bloodvessels, in 

 others there may have been some interference with the lymphatic system, 

 the relations of which to the nerves is at present unknown, whilst others 

 again admit of a different explanation. Take, for example, the case of the 

 eye after division of the fifth nerve. The experiments of Biittner and 

 Meissuer, 2 v. Bezold, 3 v. Hippel, and others, have shown that if the eye be 

 carefully covered and protected from external lesion, no pathological lesions 

 occur after the section, whilst if it be exposed, ulceration soon sets in. Here 

 it is probable the loss of sensibility of the cornea leads to dryuess, and the 

 entrance of foreign bodies, in consequence of the ordinary act of winking 

 being neglected, and such dryness is a predisposing cause to inflammation. 

 In a case under the care of the Editor, in which the fifth was paralyzed on 

 both sides, one eye was wholly lost, but in the other incomplete ptosis oc- 

 curred, and the inflammation was long limited to the part of the cornea 

 exposed in the half-shut condition. In this part a deep ulcer formed, whilst 

 the rest of the cornea was perfectly bright and transparent, and the iris was 

 not implicated till a very late period. In like manner Brown-Sequard has 

 shown that many of the effects which may be observed to follow injuries of 

 the nerves of the extremities, may be referred to a want of power on the 

 part of the animal, both to perceive and to withdraw them from irritating 

 and depressing conditions (cold, wet, and pressure). Jt must be remem- 

 bered also that many of Mitchell's cases were severe gunshot wounds, and 

 that the bloodvessels and other tissues besides the nerves were always im- 

 plicated. 4 



721. The influence of particular conditions of the Mind, in exciting, sus- 

 pending, or modifying various Secretions, is a matter of daily experience. 

 The Lachrymal secretion, for example, which is continually being formed to 

 a small extent for the purpose of bathing the surface of the eye, is poured 

 out in great abundance under the moderate excitement of the emotions, 

 either of joy, tenderness, or grief. It is checked, however, by violent emo- 

 tions ; hence in intense grief, the tears do not flow ; and it is a well-known 

 indication of moderated sorrow when the gush takes place, this very act 

 affording a further relief. The flow of Saliva, again, is stimulated by the 

 sight, the smell, the taste, or even by the thought of food, especially of 'such 

 as is of a savory character. On the other hand, violent emotion may sus- 

 pend the salivary secretion ; as is shown by the well-known test, often re- 

 sorted to in India, for the discovery of a thief amongst the servants of a 

 family, that of compelling all the parties to hold a certain quantity of rice 

 in the mouth during a few minutes, the offender being generally distin- 

 guished by the comparative dryness of his mouthful at the end of the ex- 



1 Amer. Journ. of Med. Sci., October, 1870, and New York Mod. Journ., No. 69, 

 p. 579: 



2 Berichtiib. die Fortsch. d. Phys , 1862, p. 412. 3 Doutsche Klinik, 1867. 



4 Ludwia; and Hafiz, Arbeiten, 1870; Practitioner, x, 1873, p. 146. See also 

 Hermann Schulz, Ueber den Einfluss der Nervendurchschneidung auf Ernahrung, 

 Oritralblatt f. d. Med. Wiss., 1873, p. 708 ; Joseph Keichert's Archiv, 1872, No. 2; 

 Fischer, Journ. of Anat. and Physiolog., vol. vi, p. 222 ; Vulpian, Comptes Rendus, 

 1872, t. Ixx, No. 15. 



66 



