494 STAHL, HOFFMAN, AND CULLEN. 



posed to be conveyed to all parts of the system 

 with the blood, which was thought to be the im- 

 mediate source of all diseases. But after the 

 attention of physiologists was awakened to the 

 importance of the brain and nerves, by the re- 

 searches of Willis, Malpighi, and others, it was 

 maintained by Stahl, Hoffman, and Mead, that 

 all the functions of animal life, whether vege- 

 tative or sentient, are immediately dependent on 

 the nervous system ; that some peculiar and 

 refined species of fluid, which they regarded as 

 identical with the animal spirits of the ancients, 

 was secreted by the brain, and conveyed to all parts 

 of the body through the nerves. It must, however, 

 be confessed, that the neuro physiologists never 

 explained what enables the brain to secrete ; how 

 the solids are formed from the blood ; what en- 

 dows the blood with the power of vitalizing all 

 the organs ; in what way the eggs of animals 

 are hatched by nervous influence; nor how the 

 life and growth of vegetables, including many of 

 the lower orders of animals that have no nerves, 

 are sustained. 



Yet the celebrated Cullen was so pleased with 

 the above fanciful hypothesis, that he represents 

 the brain as necessary to the action of the vital 

 principle, and the primary source of animal mo- 

 tion, whether voluntary or involuntary. He further 

 maintained that all diseases should be referred 

 to some preternatural condition of the nervous 

 system ; that cold, miasmata, fatigue, the de- 



