. Transactions . Posterior view of the h(>ad, showin<^ the open spinal canalwith the absence of the medulla. Tlie spinal accessorynerve can be seen throu<^h the thin skin covering theforaijien. at formation of the chiasma, which does not develop untilthe eyes take up the anterior position in the head which,in the process of evolution from the lower animals, is asso-ciated witli binocular vision. The condition about to be describetl in the foetus under * Figs. 34—:U). KKIIXA AM) OITIC NKinKS IX AN KN( KIll A I. V. I)) observatiuii was an arrest ot (Icvcloptnciit oi tlie bruin inthis ea
. Transactions . Posterior view of the h(>ad, showin<^ the open spinal canalwith the absence of the medulla. Tlie spinal accessorynerve can be seen throu<^h the thin skin covering theforaijien. at formation of the chiasma, which does not develop untilthe eyes take up the anterior position in the head which,in the process of evolution from the lower animals, is asso-ciated witli binocular vision. The condition about to be describetl in the foetus under * Figs. 34—:U). KKIIXA AM) OITIC NKinKS IX AN KN( KIll A I. V. I)) observatiuii was an arrest ot (Icvcloptnciit oi tlie bruin inthis early sta<»e wlion the ])riniary and socondary optic-vesicles are nornnilly formed and the nerve sheathdifferentiated, bnt before the f(^rnmtion of any axiscylinders or chiasnia. ^ihe f(etus was born ;it fall term,and, apart from the head and central nervous system, wasfully develo])e!l and presented no deforTiiities. It was. Front viow of the inacorated skull, sho\vin<, the shalloworbits with wide sphono-iiiaxillarv tissiires. obtained in a perfectly fresh condition. The globesexternally appeared normaL The frontal eminences werevery deficient, and the lack of development of the frontalbone gave a false impression of proptosis somewhatsimilar to that found in those cases of deformity of theskull the extreme degree of wliich have been described byPower,^ and lesser degrees by Dodd and .M;KMullen,t and * Ophth. Soc. Trans., 1S1)4, p. 2lL».t Lancet, June 13th, 1903. 156 DISEASES OF THE KETINA AND CHOROID. Duiialdson.^ The vault of the skull was abseut. Thescalp over the ill-developed frontal bone was thick andcovered Avith haii*^ whilst that covering the base of theskull was very tliin^ allowing the bones covered by duramater to be seen through it. This w^as especially so in theregion of the rudimentary foramen magnum, Avhere thesheath of the s]unal accessory and other cranial nerves Fig. 40.
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Keywords: ., bookcentury1800, bookdecade1880, bookpu, booksubjectophthalmology
