124 BACTERIOLOGICAL AND ENZYME CHEMISTRY 



There is evidence also that the amylase secreted, e.g., by 

 the growing plant embryo and by growing micro-organisms, 

 is somewhat different chemically from the amylase secreted 

 by the purely vegetative organs of plants, e.g., the leaf cells, and 

 by animal cells. Thus, an amylase is secreted by the salivary 

 gland, and its presence can be demonstrated by warming a 

 little 3 per cent, starch solution with a few drops of saliva, 

 and testing with iodine and Fehling solution. The enzyme 

 can be precipitated from saliva in the usual way by means of 

 alcohol. If necessary the secretion of saliva can be stimulated 

 by inhaling a little ether. 



The presence of amylase can also be demonstrated in 

 pancreatic extract. 



Brown and Morris have exhaustively investigated the 

 conditions of formation of amylase in foliage leaves, and the 

 following description from their paper 1 will serve as a very 

 good example of the methods used in this kind of research, 

 and will usefully illustrate the application of the analytical 

 processes described in Chapter V. 



A quantity of leaves of tropaeolum majus were dried in a 

 steam oven and ten grams of the dried leaves were treated with 

 boiling water. The solution was cooled to 50 C. and digested 

 with a little amylase for two hours. The mixture was then 

 filtered and the filtrate and washings made up to 144 c.c. 



The optical activity in a 10 cm. tube was then found to 

 amount to 1*9 divisions. 100 c.c. of the solution also re- 

 duced 0-532 gram CuO, which is equivalent to 0'395 gram 

 maltose. 



This amount of maltose in a 10 cm. tube will rotate the 

 polarised ray through T54 divisions of the scale. The 

 difference between this value and the observed value, viz., 

 1'90 1*54 = 0*36, must be due to dextrin, amounting in 

 weight to 0'064 grm. 



1 ' A Contribution to the Chemistry and Physiology of Foliage Leaves/ 

 Journ. Chem. Soc. Trans. 1893, p. 629. 



