478 LECTURE XX. 



entirely. The dormant seeds do not contain any ferments, i.e., not in an 

 active form; they do not become active until the beginning of germina- 

 tion. The barley embryo does not produce diastase when absorbable sugar 

 is available for it. 



The formation of ferments among the molds is likewise influenced by 

 the nature of the nourishment. If they are provided with albumin, they 

 will produce proteolytic ferments; if they are cultivated upon starch, they 

 will form diastase. Furthermore, it is known that yeast, for example, 

 which has been cultivated for a long time on a specific substratum, can 

 be " taught " to utilize definite compounds if we gradually withdraw the 

 other nutriment. 



Closely related to these observations is the fact that the plant cells, in 

 the presence of definite products, also produce the ferments which will 

 decompose them. This is usually true of the glucoside-splitting ferments. 

 Thus we find amygdalin together with the ferment emulsin in bitter 

 almonds; while the glucoside, sinigrin, is accompanied by the ferment 

 myrosin in black pepper. 



There are numerous analogous observations in the animal kingdom. It 

 was known to Claude Bernard * that the larvae of Musca lucilia, a kind of 

 fly, possessed large stores of glycogen, but did not produce any diastase. 

 The latter appears only when these stores are required by the pupa. 



Numerous relations between the kind of food and the amount and 

 nature of the secreted digestive fluids have become known by the extensive 

 researches of Pawlow. Nervous influences dominate the production of the 

 ferments. This was evident long ago from the investigations of Claude 

 Bernard on the decomposition of glycogen in the liver. Pawlow has 

 studied this subject more carefully, as we shall see later. 



From all of these statements, we involuntarily obtain the impression 

 that fermentation processes play a large part in the whole economy of the 

 individual cell, the tissues, and finally the entire organism. This view is 

 supported by the common occurrence of such processes throughout the 

 whole plant and animal kingdoms. The fact that their activity begins as 

 soon as the life processes start indicates their importance. The ferments 

 are found in very early stages of human and animal embryos. Langen- 

 dorff 2 detected trypsin especially early. Pepsin is entirely absent among 

 the carnivora just after birth, but is found in the herbivora. Diastase is 

 absent from human beings and rabbits previous to birth. The ferments, 

 evidently, play a part not only in physiological relations, but also in patho- 

 logical ones. Thus, we observe that fibrin from the bronchial tubes 

 during croupous-pneumonia is gradually dissolved and finally disappears. 3 



1 Revue scientifique (1873), p. 515. 



a Arch. Anat. Physiol. 1879, 95. 



3 F. Miiller: Verhandl. XX. Kongresses in. Med. zu Weisbaden (1902). 



