CHANGES DURING SECRETION. 485 



general convulsions; he considers that the saliva obtained in the 

 curarised animal is due to an irradiation of nervous impulses, and not to 

 a localised cortical stimulation. 



Kiilz l obtained no secretion from the submaxillary gland in unansesthet- 

 ised dogs on stimulating the facial area, unless there was general tetanus, a 

 condition in which Braun 2 had already observed a flow of saliva from the 

 mouth. Lepine and Bochef ontaine 3 obtained secretion in curarised dogs by 

 stimulating the anterior portion of the cortex, including the facial area. The 

 secretion was more abundant on the side stimulated. Bochefontaine, 4 shortly 

 after, gave a more detailed account of the parts of the cortex from which 

 secretion could be induced ; secretion was obtained by stimulating spots on the 

 posterior part of the brain, and also by stimulating parts of the dura mater. 

 The experiments show little or nothing as regards the question whether there 

 are special areas in the cortex connected with the secretion. 



Bechterew and Mislawsky 5 found, also on curarised dogs, that the region 

 which caused secretion when stimulated with weak currents was more limited 

 than that described by Bochefontaine. Stimulation of the anterior Sylvian and 

 anterior composite convolutions caused secretion from both the submaxillary 

 and parotid glands. Stimulation of the anterior limb of the sigmoid gyrus, 

 and of the anterior extremities of the coronal and anterior ecto-Sylvian con- 

 volutions, caused secretion from the submaxillary gland only. With stronger 

 currents, secretion was sometimes obtained from the more posterior portions of 

 the cortex. They found, unlike Lepine and Bochefontaine, no effect on 

 stimulating the orbital convolution. 



CHANGES IN SALIVARY GLANDS DURING SECRETION. 



The changes which occur in salivary glands during secretion are 

 progressive, and there is no sufficient reason for believing that the 

 changes which occur in the cells at the end of a day's active secretion 

 differ in kind from those which occur in the first ten minutes. 



The evidence is, it seems to me, decisively against the view that 

 during salivary secretion there is a breaking down of the mucous or of 

 other gland cells. 6 If saliva at any stage of secretion is allowed to run 

 into alcohol, mercuric chloride, or other hardening reagent, disinte- 

 grating cells are not seen in the sediment as it forms, nor nuclei beyond 

 those which arise from the separated cells of Wharton's duct and from 

 leucocytes. And in the gland itself there is at no stage any sign of 

 active cell division ; the nuclei undergoing mitotic division are as rare 

 as they are in the resting gland. 7 



Two fundamental changes undoubtedly take place in the gland cells 

 during secretion. 



There is, first, an excretion of a greater or less amount of the sub- 

 stance which has been previously formed in the cells ; 8 this substance, 



l Centralbl.f. d. med. Wissensch., Berlin, 1875, S. 419. 



2 Beitr. z. Anat. u. Physiol. (Eckhard\ Giessen, 1876, Bd. vii. S. 136. 



3 Gaz. med. de Paris, 1875, p. 332. 



4 Arch, de physiol. norm, etpath., Paris, 1876, p. 161. 



5 Neurol. VentralbL, Leipzig, 1888, p. 553. 



6 It must be mentioned, however, that Heidenhain in his treatise (Hermann's 

 "Handbuch," 1890, Bd. v.) maintains the view originally advanced by him, that mucous 

 cells disintegrate to form part of the secretion. 



7 Langley, Proc. Roy. Soc. London, 1886, vol. xli. p. 362 ; Bizzozero, Vircliow's Archiv, 

 1887, Bd. ex. S. 181. 



8 Heidenhain, Arch. f. d. ges. Physiol. , Bonn, 1878, Bd. xvii. S. 43; Hermann's 

 "Handbuch," 1883 ; Lavdowsky, Arch. f. mikr. Anat., Bonn, 1877, Bd. xiii. S. 335. 



