524 THE SALIVAR Y GLANDS. 



seems to have thought that these recurrent fibres ran in a single bundle 

 a considerable distance down the lingual, for he says that when the 

 lingual nerve is cut about 2 cm. beyond the point where the chorda 

 tympani leaves it, and time is allowed for degeneration, no secretion is 

 obtained by stimulating the central end : a negative result which was 

 not obtained by Wertheimer. 1 Wertheirner's positive result then may 

 be taken as showing that the recurrent fibres leave the lingual at more 

 than one spot. 



But it is nevertheless possible that on stimulating the central end of 

 the lingual a secretion should be obtained which is not produced by 

 recurrent fibres, and which is due to nervous impulses passing through 

 local nerve-cells. The nerve-cells on the course of the chorda tympani 

 are, as we have seen, scattered ; if tie chorda tympani fibres branch 

 before running to these cells, stimulation of one of the branches would 

 probably cause a nervous impulse to pass to the more central branches 

 and to the cells connected with them. This would be a reflex through 

 efferent fibres of the kind described in some other peripheral ganglia. 2 

 Such action with the actual anatomical arrangements is more likely to be 

 obtained from the sublingual than from the submaxillary gland. It 

 would, of course, be annulled by degeneration of the chorda tympani. 



DIRECT IRRITABILITY OF GLAND-CELLS. 



It is natural to suppose that stimulation of the gland-cells by 

 electrical, chemical, or mechanical stimuli should be capable of causing a 

 secretion. There is, however, no direct evidence that this is the case. 

 After atropine has been given, no secretion has been obtained ; but it 

 must be mentioned that, even when the nerve-endings in the sub- 

 maxillary gland are in a full state of irritability, it is difficult to obtain 

 secretion from it by electrical or other stimuli applied to its outer sur- 

 face, and which do not affect the internal bundles of nerves. 3 



EXTIRPATION OF SALIVARY GLANDS, INJECTION OF SALIVA INTO 



THE BLOOD. 



The extirpation of all the salivary glands is, of course, impossible ; 

 but the large salivary glands, i.e. those which secrete by far the greater 

 portion of the saliva, can be cut out. This has been done by Fehr. 4 

 He states that in the dog he removed not only the parotid, submaxillary, 

 and sublingual glands on both sides, but also the orbital glands. The 

 operation had no appreciable effect on nutrition ; and the only difference 

 in the behaviour of the animal was that it drank more water. A 

 similar result was observed by Schafer and Moore. 5 They removed 

 from a dog the parotid, the submaxillary, and the larger part of the sub- 

 lingual glands. There \vas no disturbance of nitrogenous metabolism, 

 and neither sugar nor albumin appeared in the urine. Carbohydrates 



1 Arch, de physiol. norm, et path., Paris, 1890, p. 519. 



2 Langley and Anderson, Journ. Physiol. , Cambridge and London, 1894, vol. xvi. 

 p. 410. 



" Bernard ("Lecons sur la proprieties physiologiques," etc., 1859, tome ii.) found, by 



stimulating the gland directly, that pain was caused. 

 4 Henle and Meissner's Jah\ 



Jahresb., in Ztschr. f. rat. Med., 1862, p. 255. 

 5 " Proc. Physiol. Soc.," 1896 p. xiii., Journ. Physiol., Cambridge and London, 

 vol. xix. 



