The morphology and evolutional significance of the pineal body : being part I of a contribution to the study of the epiphysis cerebri with an interpretation of the morphological, physiological and clinical evidence . posterior; (/>., posterior. posed this (juestion, If in Anguis the parietal eye is only adifferentiation of the distal extremity of the epiphysis, how inLa«r,(t does this visual organ develop parallel to the epiphysisand not dependent upon it? Beraneck maintains thai Klinc-kowstroem escapes the difficulty proposed by this question inclaiming thai the pineal eye of
The morphology and evolutional significance of the pineal body : being part I of a contribution to the study of the epiphysis cerebri with an interpretation of the morphological, physiological and clinical evidence . posterior; (/>., posterior. posed this (juestion, If in Anguis the parietal eye is only adifferentiation of the distal extremity of the epiphysis, how inLa«r,(t does this visual organ develop parallel to the epiphysisand not dependent upon it? Beraneck maintains thai Klinc-kowstroem escapes the difficulty proposed by this question inclaiming thai the pineal eye of lynuim and ;iccrl<i upon theone hand and Ainjnis upon the other take origin from differentparts of the epiphyseal evaginal ion. formulates thehypothesis that the parietal eye and epiphysis represent in THE PINEAL BODY 61 Lacerta two distinct evaginations of the thalamencephalic they appear to be different in Iguana and Anguis that is due tosecondary modifications of this region. The evolution of theparietal eye in Iguana is intermediate between the conditionsobserved in Lacerta and Anguis. In his conclusion, Beraneckemphasizes his belief that the embryonic facts contradict the Xpar. Fig. 26 Frontal section showing epiphyseal complex in a 26-day old Iguanatuberculata, according to Klinckowstroem, 1894. P/., paraphysis; Ds., dorsal sac; Npar., nervus parapinealis; Ep., proximalportion of pineal organ; Ch , commissura habenularis; M., midbrain epiphyseal origin of the parietal eye in Saurians and confirmthe hypothesis of its embryonic individuality. Leydig238 in1891 confirmed the view of Beraneck in Lacerta agilis. Dendy86also states that the parietal eye and what he calls the parietalstalk arise from two distinct evaginations in the roof-plate ofthe interbrain. By parietal stalk, Dendy refers to the portionof the epiphyseal complex here referred to as the pineal organ. - ,. w
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