4 CHEMICAL PHYSIOLOGY. 



efficiently the want of alkali and ptyaline in the diges- 

 tive juices of children who are being brought up with- 

 out mother's milk, or with such as is not in a healthy 

 state. Diastase acts best at 66 C, while ptyaline is 

 destroyed at 60 C. An agent similar to ptyaline is 

 emulsine, or synaptase of almonds, which has been 

 recommended as a dietetic remedy in diabetes. But it 

 does not seem to affect starch in any way, although 

 decomposing amygdaline and salicine. 



Oil of bitter Prassic 

 Amygdaline. "Water. almonds. acid. Sugar. 



Salicine. Water. Saligenine. Sugar. 



In these transformations sugar is a collateral pro- 

 duct, while in that of starch by ptyaline or diastase it 

 is the only product. 



starch. Starch consists of two bodies, which in the little 



granules are disposed in alternating layers. The first 

 is granulose, and has the property of being coloured 

 blue at once by free iodine. The second is cellulose, 

 not coloured blue by iodine at once, but only after 

 sulphuric acid or zinc-chloride has been allowed to act 

 upon it. When unboiled starch is mixed and digested 

 with saliva for days, the granulose is dissolved out of 

 the corpuscles and transformed into dextrine and 

 sugar, and the cellulose only is left. At higher 

 temperatures this also is changed. Boiled starch is 

 more easily transformed, as the granules are burst and 

 admit the altering juices between their layers with 



