SECT. VI.] SUBSTITUTION OF BRAIN FOR VENTRICLES. 375 



since the new serum perpetually secreted resists the retrograde 

 movement. 



He confirms the ancient opinion of Plato, that the brain is 

 an appendage to the spinal cord_, in which medullary fibres, 

 collected together, radiate towards the brain, until they end in 

 the cortical portion, just as the fibres in the stem of a cauli- 

 flower radiate into the leaves. Confirmatory of this doctrine 

 are the small brain and large spinal cord of fishes. Fracassatus 

 also adopted this opinion, and Thomas Bartholin, in his ' Ana- 

 tome quartum renovata,' says this opinion is both new and 

 peculiar, and that by it he can understand how fishes, on 

 account of their small brain, are dull as to sensation, but agile 

 as to movement, from their large spinal cord ; especially since in 

 the incubated egg also the anterior part of the brain is developed 

 at a much later stage than that in which if the chick be touched 

 it contracts. It is well known, however, that Plato had already 

 stated, that the spinal cord is first formed, and the brain is an 

 appendix to it.^ 



Thomas Willis, a celebrated member of the chemical sect, 

 advanced, with some ingenuity, many new hypotheses as to the 

 uses of the nervous system ; with these he commingled some 

 ancient doctrines, as for example, that serous effete matter in 

 the ventricles trickles partly through the olfactory nerves into 

 the nostrils, partly through the infundibulum to the pituitary 

 gland, and thence by peculiar ducts to the veins which return 

 the blood to the heart from the brain ; he also agreed with Galen 

 in considering the use of the fornix to consist in supporting the 

 hemispheres. His own peculiar doctrines chiefly are : that the 

 cerebrum subserves to the animal functions and the voluntary 

 motions, the cerebellum to the involuntary ; that a perception 

 of all the sensations takes place in the ascending fibres of the 

 corpora striata, and that through the descending, voluntary move- 

 ments are excited ; that the understanding is seated in the corpus 

 callosum, and memory in the convolutions, which are its store- 

 houses ; that the animal spirits are generated in the cortex of 

 the cerebrum and cerebellum from the arterial blood ; that they 

 collect in the medulla, are variously distributed and arranged 

 to excite the animal actions, and distil through the fornix 

 as if through a pelican : that the animal spirits secreted in 



' Ilaller, Bib. Anat., torn, i, p. 30. 



