Three views of this brain are given in Plate II, figs. 1, 2, 3,
of the work cited, shewing the upper, lateral and inferior views
of the hemispheres, but not the inner view. It is worthy of note
that the figure by no means bears out Gratiolet's description,
inasmuch as the fissure (antero-temporal) on the posterior half
of the face of the hemisphere is more marked than any of those
vaguely indicated in the anterior half. If the figure is
correct, it in no way justifies Gratiolet's conclusion: "Il y a
donc entre ces cerveaux [those of a Callithrix and of a Gibbon]
et celui du foetus humain une difference fondamental. Chez
celui-ci, longtemps avant que les plis temporaux apparaissent,
les plis frontaux, ESSAYENT d'exister."

Since Gratiolet's time, however, the development of the gyri and
sulci of the brain has been made the subject of renewed
investigation by Schmidt, Bischoff, Pansch (78. 'Ueber die
typische Anordnung der Furchen und Windungen auf den Grosshirn-
Hemispharen des Menschen und der Affen,' 'Archiv fur
Anthropologie,' iii. 1868.), and more particularly by Ecker (79.
'Zur Entwicklungs Geschichte der Furchen und Windungen der
Grosshirn-Hemispharen im Foetus des Menschen.' 'Archiv fur
Anthropologie,' iii. 1868.), whose work is not only the latest,
but by far the most complete, memoir on the subject.

The final results of their inquiries may be summed up as
follows:--

1. In the human foetus, the sylvian fissure is formed in the
course of the third month of uterogestation. In this, and in the
fourth month, the cerebral hemispheres are smooth and rounded