His last writings were memoirs on the convolutions of the human brain, on the weight of brains, and on the brains of idiots (1860-1862).
The brain differs little, except in details of arrangement of convolutions, from that of other ungulates.
There is very little grey matter in the cortex of the hemispheres, the surface of which is devoid of convolutions, mostly quite smooth; in others, for instance pigeons, fowls and birds of prey, a very slight furrow might be compared with the Sylvian fissure.
Configuration of the palate, precoracoid, pelvis, intestinal convolutions, copulatory organ, &c. Loss of the keel is co-ordinated with the power of using the forelimbs for locomotion; although a " Ratite " character, it is not sufficient to turn a Notornis, Cnemiornis or Stringops, not even a Phororhacos into a member of the Ratitae.
When therefore sensible uniformity is desired, the radius of the ring should he large in relation to that of the convolutions, or the ring should have the form of a short cylinder with thin walls.
For the osculating circle at any point includes the whole of the y curve which lies beyond; and the successive convolutions envelop one another without intersection.
The cerebral convolutions remain unaffected, but the important centres of the medulla oblongata are stimulated.
While similar as to their general arrangement to the human brain, those of the higher apes, such as the chimpanzee, are much less complex in their convolutions, as well as much less in both absolute and relative weight - the weight of a gorilla's brain hardly exceeding 20 oz., and a man's brain hardly weighing less than 32 oz., although the gorilla is considerably the larger animal of the two.
The Pacific coast-line, omitting minor convolutions, has a length of about 500 m., while that of the Caribbean is about 700 m.
Long and its convolutions are few and simple.
The convolutions are held together by the pelvic cellular tissue, and by involuntary muscle continuous with that of the bladder.