CHAP. I.] SUBLINGUAL SALIVA. 33 



in a manner which is only intelligible by assuming that these act 

 through a nerve centre. 



Langley has found that 'injection of dilute salt 

 solution in moderate quantity increases the rate of 

 sat soluton secretion of saliva with a given stimulus, the percent- 

 into the blood, age of salts in the saliva rising nearly normally ; and 

 that injection of dilute salt solution in larger quantity 

 increases further the salivary secretion with a given stimulus, but in 

 this saliva the percentage of salts rises much less than normally, and 

 may even fall 1 .' 



Effect of in- Langley investigating the action produced when a 



jecting into wea k solution of sodium carbonate is introduced into 



2 per cent tne blood, arrived at the conclusion that ' the injection 



solution of considerably increases the rate of secretion obtained by 



Na 2 co 3 . a stimulation of given strength of the chorda tympaniV 



4. SUBLINGUAL SALIVA. 



According to Heidenhain 3 , the sublingual saliva of the dog forms 

 a viscous mass to which the term fluid can scarcely be applied, and 

 which bears a resemblance to frog's spawn. Sublingual saliva is free 

 from all turbidity, being perfectly transparent and clear. It gene- 

 rally contains a large number of amoeboid corpuscles. The 'para- 

 lytic ' saliva of the sublingual gland is about as viscous as the normal 

 chorda-saliva, and, therefore, very different in character from paralytic 

 submaxillary saliva. 



"The very viscous condition of sublingual saliva is the result of a 

 kind of * clotting ' of the saliva. When the chorda tympani is stimulated 

 iii a dog, the sublingual saliva obtained is usually not especially thick, but 

 in a short time it turns to a jelly, and a little clear watery fluid may be 

 pressed out. When the 'jelly' is obtained from the duct, it is probably 

 because the saliva has clotted there (Langley 4 )." 



The only analyses of sublingual saliva with which the author is 

 acquainted are four made. by Werther and a single one by Langley 

 and Fletcher. Werther, as the result of a research undertaken under 

 the direction of Heidenhain, has drawn attention to the remark- 

 ably interesting fact that the extraordinary viscidity of sublingual as 

 contrasted with submaxillary saliva does not depend, as had been 

 surmised, on its containing a much larger proportion of organic solids 

 and especially of mucin, for the amount of water in sublingual saliva 



1 J. N. Langley and H. M. Fletcher, ' On the Secretion of Saliva. Chiefly on the 

 secretion of salts in it.' Philosophical Transactions, Vol. 180 (1889) B, pp. 109 154. 

 See p. 129. 



2 J. N. Langley and H. M. Fletcher, Op. tit. p. 134. 



3 Heidenhain, Studien des physiol. Instituts zu Breslau. 



4 Privately communicated to the author. 



G. 3 



