820 ANIMAL PHYSIOLOGY, 
tomical relations of the salivary glands in some mammal, we 
would further remind him that the submaxillary gland has a 
double nervous supply: 1. From the cervical sympathetic by 
branches passing to the gland along its arteries. 2. From the 
chorda tympani nerve, which after leaving the facial makes 
connection with the lingual, whence it proceeds to its destina- 
tion. 
Part of brain above medulla 
Secretory centre 
in medulla 
Blood vessel 
f of gland 
Afferent nerves }+Superior cerv. ganglion 
from tongue ---~ 
| Sympathetic nerve 
Fie. 273.—Diagram intended to indicate the nervous mechanism of salivary secretion. 
The following facts are of importance as a basis for conclu- 
sions: 1. It is a matter of common observation that a flow of 
saliva may be excited by the smell, taste, sight, or even thought 
of food. 2. It is also a matter of experience that emotions, as 
fear, anxiety, etc., may parch the mouth—i. e., arrest the flow of 
saliva. The excited speaker thus suffers in his early efforts. 
