UPON THE SERIES OF PllEHISTOEIC CRANIA. 667 



into this difference a little more closely, we find that if we take for 

 our posterior limits, not the posterior aspect of the skull but the 

 plane of the lambdoid suture, the two varieties of skull are just as 

 clearly differentiated as before. For the relative proportions of 

 that portion of the cerebral cranium which is constituted by the 

 superior squama occipitis and lodges the occipital lobe proper, and 

 the relative proportions of that lobe itself, are exceedingly variable^ 



^ The occipital lobe is supplied exclusively by tlie posterior cerebral artery, which, 

 on account of the angle which it makes with the main trunk whence it arises, 

 the basilar, namely, or, on the right side, very frequently the internal carotid, 

 as also on account of its great length, must work at very considerable hydraulic 

 disadvantage. What the peculiar course of the artery would lead us to anticipate, 

 the peculiarities of the veins of this j^ortion of the cerebrum confirm us in holding. 

 One of the largest of the Pacchionian bodies is ordinarily found at the point where the 

 veins of the occipital lobe enter the superior longitudinal sinus, this point being upon 

 the line of the parieto-occipital fissure, and corresponding with what is usually the 

 most posteriorly placed of thefovecB glandidares in the skull. Now the bodies known 

 as Pacchionian glands are growiihs which in their normal state are biit -pg— | mill. 

 in size, and which owe the increase in size which makes them prominent to the eye 

 and impresses them on the skull to venous congestion. The very constant presence 

 therefore of a largely hypertrophied Pacchionian body upon the embouchure of the 

 occipital veins is a significant fact as regards the retardation of their cun-cnt (Wilks 

 and Moxon, in their ' Pathological Anatomy,' p. 208, compare these bodies to the 

 papillose outgrowths sometimes seen on the sm-face of the liver in cases of extreme 

 cardiac congestion). The amenability of the Pacchionian bodies to pathological change 

 is recognised by Rokitansky, ' Pathological Anatomy,' English translation, 1850, 

 vol. iii. p. 329, or 2nd German edition, 1856, vol. ii. p. 407 ; by Jones and Sieveking, 

 in theii* ' Manual of Pathological Anatomy,' edited by Dr. J. Frank Payne, 1875, 

 p. 237 J by Wilhelm Krause, in his ' Handbuch des Menschlichen Anatomic,' 3rd ed., 

 1876, p. 460 ; and finally by Luschka, who was, as far as I know, the first to di-aw 

 attention to the fact that in their earlier stages and smaller size these bodies could 

 not be considered other than normal growths, in his ' Anatomic des Menschen,' 1865, 

 Bd. iii. Abtheilung ii. p. 240. 



The histological inferiority of the occipital lobe Is well known, and though Mr. 

 Lockart Clarke may slightly overstate the case when he says (Maudsley, Physiology 

 of Mind, 3rd edition, 1876, pp. 112 and 114) that ' all the nerve-cells are small,' both 

 Professor Turner (Introduction to Human Anatomy, part i. 1875, p. 283) and Pro- 

 fessor Henle (Handbuch der Syst. Anatomic, iii. 2, p. 276) would allow that 'the 

 gi-eater number of the cells of the occipital lobe are small and nearly uniform in size,' 

 and, what is of equal importance, that the superficial layer, which is everywhere poor 

 in cell-elements, is of greater width in the occipital than in any other region of the 

 brain. Meynert's words (Strieker's Manual of Human and Comparative Histology, 

 English translation by Power, vol. ii. p. 391, 1872) are eminently to the purpose : ' The 

 brain of monkeys, which is distinguished by excessive development of the occipital 

 lobes, contains this type of tissue (the pyramidal cells) in much greater abundance than 

 the human brain.' Dr. Herbert C. Major has given an instructive account of the 

 histology of the brain of the Chacma Baboon in the Journal of Mental Science, 

 Jan. 1876, and refers therein to Meynert's memoir, I. c. 



As regards the connexion of the occipital lobes with mental functions, it is well 

 knowTi that Neumann (cit. Cruveilhier, Anat. Descript., ed. 1836, iv. p. 668 ; Longet, 

 Systeme Nerveux, i. 691, and Traite de Physiologic, 1869, iii. p. 444) was induced 

 from his examination of the brains of some fifty insane persons to hold that intelligence 

 had its seat in the occipital lobes ; and Cruveilhier is also quoted as speaking in the 



