SALIVATION. 217 



line (Berzelius) or animal diastase (Mialhe), resembling 

 closely the principle of sprouting barley. This substance 

 has the property of changing starch into glucose. The 

 parotid saliva alone has no power to change starch into 

 sugar (in the horse, and in man) ; the case is the same with 

 the sub-maxillary gland (the dog) : the power of turning 

 substances into sugar thus appears to belong to the complex 

 product of the different salivary glands and of those glands, 

 called mucous, which are so abundant in the buccal cavity. 

 This property does not appear to belong exclusively to the 

 saliva: it is found in nearly all animal substances; the mu- 

 cous of the bladder, the blood, and the muscular flesh all 

 have it though in a low degree. 



The saccharizing property of the saliva is not equally 

 prominent in all animals : man is one of the most favored in 

 this respect, but less so than some of the herbivora, especially 

 the guinea-pig ; the saliva of the dog, so often made use of 

 for experiments, is not well adapted for this purpose, possess- 

 ing the property, as it does, in a much lower degree than 

 many others. In man, this property is developed only 

 with the first appearance of the teeth (Bidder). The ptya- 

 line of the saliva can only be extracted by precipitating it by 

 alcohol, and then redissolving it in water (general process 

 of separation of the albuminoid ferments). In all salivary 

 ptyaline are found peculiar elements of a globular form, 

 called by some authors pyoid globules, and closely resem- 

 bling the white globules. Leeuwenhoek had already dis- 

 covered these globular elements, which exhibit decided 

 phenomena of amoeboid movements, and are reproduced by 

 means of fission ; these inferior organisms may be compared 

 to ferments, and have a more or less direct part in producing 

 the chemical activity of the saliva ; indeed we notice that 

 the more abundant these organisms are, the greater is the 

 saccharizing property of the saliva; thus, in salivation 

 (ptyalism) produced by the use of mercury, Leeuwenhoek's 

 corpuscles are extremely numerous, and the saliva has the 

 property of changing starch into sugar in the highest degree 

 (Rouget). 



Ptyaline is a soluble ferment ; it partakes of the nature 

 of an albuminoid, but differs a little from other albuminoids 

 in not being precipitated by a heat of 60 (C) ; this does 

 not, however, imply that it is not destroyed by an increase 

 of temperature (Frerichs, Cohnheim), but the temperature 

 must be raised at least to the boiling point in order to effect 



