SALIVARY CALCULI. 27 



Hence it might be expected that it would, at all events, have been 

 more accurately examined in persons with ptyalism, in which it is se- 

 creted in large quantities, but such is not the case. Wright has 

 indeed given an exposition of those cases in which a symptomatic, a 

 critical, or an artificially induced ptyalism occurs ; but we do not 

 the less miss analyses susceptible of chemical and physiological 

 application. The secretion in cases of mercurial salivation has as 

 yet been the most carefully studied. The results obtained by 

 Wright, L'Heritier, Simon, and myself, perfectly coincide in the 

 following points. At the commencement of mercurial salivation 

 the buccal mucous membrane and the tonsils are more affected 

 than the salivary glands, and hence the expectoration is more 

 viscid, of a higher specific gravity, and richer in solid constituents, 

 especially epithelium and mucus-corpuscles, than normal saliva ; it 

 is very turbid, from the presence of more or less distinct flocculi ; 

 has an alkaline reaction ; contains little of the peculiar principle, 

 ptyalin, often much fat, and rarely any appreciable quantity of 

 sulphocyanide of potassium. At a later period, when the salivary 

 glands become the seat of pain and swelling, a less turbid saliva is 

 secreted, which often contains a much smaller amount of solid 

 constituents than normal saliva ; it is still alkaline, and sul- 

 phocyanide of potassium is more often absent than present ; it is 

 also rich in fat, and often in mucus-corpuscles. We have already 

 noticed the presence of mercury in this variety of saliva. 



In conclusion, we must mention salivary calculi as morbid 

 products of this secretion : they have been very often analysed, 

 and have been found to contain more carbonate of lime than any 

 other kind of concretion. As we have already shown that the 

 saliva even of carnivorous animals holds in solution no inconsider- 

 able quantity of lime in combination with organic matter, and that 

 the lime is very readily separated from this compound as a 

 carbonate, we have no difficulty in comprehending the mode of 

 formation and the constitution of these concretions. 



The quantity of saliva excreted in a given time is a point regard- 

 ing which there is a tolerable coincidence amongst the statements 

 of authors, although we cannot regard it as definitively established; 

 for most writers have based their calculations on the data of 

 Mitscherlich, which refer merely to the parotid secretion of a man 

 labouring under disease.* The patient in the case referred to, after 

 collecting the saliva in the mouth for 15 minutes, ejected from it 



* [Lehmann should have mentioned that in this case the patient had a 

 parotid fistula. G. E. D.] 



