416 Chapter XIII 



heated to 60° C. Against certain micro-organisms — the torulae 

 and the staphylococci — the heated saliva acted more vigorously 

 than did the unaltered saliva. It is consequently impossible to 

 draw any parallel between the action of the saliva and that of the 

 cytases. 



Since the saliva often contains (according to certain authors even 

 constantly) small quantities of potassium sulphocyanide, it seemed to 

 be worth while to ascertain whether this salt is capable of destroying 

 micro-organisms. The experiments carried out by Hugenschmidt, in 

 order to settle this point, demonstrated that when given in doses 

 comparable to those met with in the saliva, the potassium sulpho- 

 cyanide exerts no bactericidal action. 



Powerless as an antiseptic, the saliva fulfils an important function 

 in ridding the mouth of micro-organisms in a mechanical way. The 

 parotid secretion and that of the other salivary glands dilutes the 

 bacteria and carries them from the pharyngeal cavity into the stomach. 

 Hence, in diseases where the salivary secretion is much diminished, 

 the mouth becomes the most important portal of entry for micro- 

 organisms capable of setting up secondary infections. The saliva 

 is further useful in diluting the alimentary detritus and preventing its 

 stagnation and decomposition in the buccal cavity. 



In addition to the direct mechanical part played by the saliva, 

 it performs a very important indirect function. This fluid con- 

 tains microbial products and diastases, and is capable of exciting 

 in the leucocytes a positive chemiotactic activity. Hugenschmidt 

 demonstrated the fact by introducing into animals small capillary 

 glass tubes containing saliva. A certain time after being placed in 

 position, these tubes became filled with considerable masses of immi- 

 grated leucocytes. The same result was obtained with guinea-pig's 

 [437] saliva, enclosed in capillary tubes and introduced into the peritoneal 

 cavity of the same species. Here, again, the leucocytes assembled in 

 the tubes and ingested the micro-organisms found in the saliva. The 

 influence of the saliva on the afflux of the leucocytes must be regarded 

 as an act important for the protection of the buccal cavit} , and it is 

 probably due to this attraction of leucocytes that lesions of this 

 region heal so quickly. The leucocytes are very numerous in the 

 glands of the mouth and the tonsils always supply large quantities 

 of them. 



We must not lose sight of the fact that the epithelial covering of 

 the buccopharyngeal cavity also constitutes an important protective 



