Volume 1

Scientific papers and addresses / by George Rolleston ; arranged and edited by William Turner ; with a biographical sketch by Edward B. Tylor.

Date:
1884
Catalogue details

Licence: Public Domain Mark

Credit: Scientific papers and addresses / by George Rolleston ; arranged and edited by William Turner ; with a biographical sketch by Edward B. Tylor. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

    121/590 (page 39)
    where phrases it), we are always justified, if we can recognise the suture which limits the frontal from the parietal bone, in saying that under it will be found lying the convolution numbered 41. I know not what, nor whether any, functions have been localised along this sutural arc. Our third and last great boundary line is the so-called external perpendicular fissure which is lettered E m the Diagrams. It is upon the upgrowtb in man within this fissure of convolutions (lettered a and ^ in the Diagrams), stunted else- where, that so much weight has been laid. They are in him connecting table-lands elevated from the lower position of spurs and sloping declivities. (See Figures 3 a, 3 b.) We see them neither in the chimpanzee nor in the mandrills. (See Figures 4b, 5 a.) The external perpendicular fissure (^) has taken their place. In the orang (Fig. 4 a) and the Ateles (Fig. 5 b) we again see the letters a and /3 which betoken them. The lobe numbered 10, il, 12, which they connect with one numbered 5 and 4, is the occipital; the one numbered 5 and 4 is the parietal. The fissure of Sylvius separates this lobe from the temporo-sphenoid, numbered 7, 8, 9. The lobe in front of the parietal numbered i, 2, 3 is the frontal. We have become acquainted then with four great divisions in the brain surface, and that each admits of an easy division into three minor convolutions the diagrams sufficiently show. I shall not enumerate all the twelve with their distinctive peculiarities and several grades of development; the three divisions—the upper, lower, and middle stages as they may be called—of the frontal lobe are, however^ of importance to us even in this hurried and imperfect comparison. The bridging convolutions have in name the physiological importance of a primary lobe ; morphologically, of course, they cannot hold this rank. A lobe hidden from our eyes, and in the depths of the Sylvian fissure, holds just the reverse relation to morphological and physiological considerations, it is present in all the subjects of our comparison, and is the centre point round which the other convolutions can be most naturally grouped; but physiologically it is of little moment; known as 'the island of Reil' it completes the number, five, of which we spoke as being the number of the great brain divisions. ' [Gratiolet was in eiTor in placing this convolution under the fronto-parietal suture, for the fissure of Rolando is always situated some distance behind that suture.— Editor.]