structure of the brain and nerves , & c. 
2 9 
chiefly of globules from to 4^0 of an inch in diameter ; 
and the smaller globules prevail. The single globular fibres 
are not so readily distinguished as in the other parts of the 
brain ; the gelatinous mucus and fluid resembling serum, 
are very abundant. The finest and most delicate branches 
of the arteries and veins are only found in the cortical sub- 
stance. 
The medullary substance of the cerebrum and cerebellum 
differs from the above in the large globules prevailing ; the 
mucus being more tenacious and less in quantity in proportion 
to the globular tissue, and the single globular fibres being more 
distinct, and the arterial and venal branches being larger. 
The crura cerebri and cerebelli resemble in general the 
medullary substance, only that the mucus and fluids are more 
abundant ; and there appears a greater proportion of mucus 
than globules ; the blood vessels are larger than in the me- 
dullary substance. 
The medulla oblongata, the corpora pyramidalia and oli- 
varia have nearly the same structure as the medullary sub- 
stance ; the single globular fibres, and their bundles, are 
composed of the larger globules ; the mucus, however, is 
very abundant, and is sooner dissolved in water than the 
mucus in any other part of the brain. 
The pons verolii is principally composed of globules 
of an inch ; the fibres not quite so distinct as in the me- 
dulla oblongata ; the mucus very abundant. The medulla 
spinalis has the globules of to of an inch pre- 
dominant ; the mucus and fluid less tenacious, but in greater 
quantity than in any part of the brain; for this reason, the 
single globular fibres are not so readily discovered ; for if 
