ORGANS OF THE BODY. 465 



the dog. These are entirely absent, it is stated, in the chorda 

 saliva. 



The fluid excreted by the submaxillary gland contains farther, as was 

 observed by Heidenhain, in the first place, cast-off mucous cells ; either 

 those of the gland vesicles intact, or changed by maceration and swollen 

 up, the result of which is the production of a multitude of peculiar round 

 and very pale masses, like drops of some viscid substance. Besides 

 these, saliva corpuscles are present in the secretion, i.e., small lymphoid 

 cells in various stages of development, and which have wandered out with 

 the fluid. 



When one of the two secretory nerves of the submaxillary gland is 

 irritated uninterruptedly for a considerable period, the number of these 

 salivary corpuscles be- 

 comes naturally in- 

 creased. Another effect 

 of this proceeding is 

 further seen, as was 

 pointed out by Heid- 

 enhain, in an extraor- 

 dinary transformation 

 of the interior of the 

 gland (fig. 445). In 

 the greater number of 

 the vesicles the mucous 

 cells are found to have 



entirely disappeared, Fiff- 445._Submaxillary gland of the dog with its contents, a, niodi- 



granular ^ e< ^ by strongly stimulating the chorda tympani; 6, unchanged 

 ? residue : after Heidenhain. 



nucleated elements, 



smaller than the original cells, occupying their place. The explanation is 

 simply this, that these cells have parted with their mucus, and have 

 again become filled with protoplasm (Ewald, Rheiner). 



In man the saliva of the submaxillary gland contains a large quantity 

 of mucin dissolved in an alkaline fluid, together with a sugar-forming 

 ferment and sulphocyanogen ( 38), which latter is also found in the sub- 

 lingual and parotid secretions. In the saliva of the lower animals, on 

 the other hand, this compound is not to be found. 



The secretion of the sublingual gland has, up to the present, excited 

 but little attention. According to Heidenhain, the organ is presided 

 over by the same nerves as the submaxillary gland in the dog, namely, 

 the facial and sympathetic. Stimulation of the chorda tympani causes 

 here also an increased flow of the secretion. 



The saliva of the sublingual gland is an extremely tenacious and 

 completely transparent substance, which can hardly be called a fluid. Its 

 reaction is alkaline, and its percentage of solid constituents about 275. 



The product of the parotid finally may be increased by irritation of one 

 of the cranial nerves, namely, the lesser superficial petrosal, a branch of 

 the facial (Ludwig, Bernard). Stimulation of the sympathetic also has 

 the same effect (Eckhard, von Wittich, Nawrocki). The fluid thus 

 obtained has a much less alkaline reaction than that of the submaxillary 

 gland. It is always thin, and never in the least viscid. The secretion 

 of the parotid, further, has no reaction on mucin, and contains from five 

 to six per cent, of solid constituents (Ordenstem) ; also albumen, and, 

 as already mentioned in the human subject, sulphocyanogen combined with 



