6 



mistry lias taught us hitherto, has the smallest 

 analogy to the operation of the nervous system, 

 or affords us the least hint toward a knowledge of 

 its occult nature. And the chain of our experi- 

 ence must always end in something inconceiv- 

 able; unfortunately, this inconceivable something 

 acts the principal part in Animal Chemistry, and 

 enters so into every process even the most mi- 

 nute, that the highest knowledge which we can 

 attain, is the knowledge of the nature of the pro- 

 ductions, whilst we for ever are excluded from 

 the possibility of explaining how they are pro- 

 duced. Permit me here to shew by an example 

 the embarrassment of the studenj: of Animal Che- 

 mistry on all occasions, when the inconceivable 

 nervous system exercises its operations : It is 

 well known that blood, which is always formed 

 from the food of the animal, is the raw material 

 out of which the body recruits and re-produces its 

 parts; and that this blood, which is every where 

 of the same nature, is conveyed through the ar^ 

 teries to the different parts of the body. From 

 this blood the kidneys form urine ; the glands near 

 the ear and under the tongue, saliva; those in the 

 breasts of women, milk; and so forth: all which 

 are humours of the most different nature. The 

 most acute anatomical investigation has proved, 



