THE CENTRAL NERVOUS SYSTEM 729 



milestones in the march of development. The pineal body is made 

 up of the vestiges of the unpaired mesial eye of such animals as 

 the ancient labyrinthodonts, which resembled the eye of invertebrates 

 in having the retinal rods directed towards the cavity instead of 

 towards the circumference of the eyeball. In many living forms, 

 especially in certain lizards, this pineal or parietal eye is found in 

 a more perfect condition, though covered by a thin membrane. The 

 ganglia habenulfz seem to represent the optic ganglia of this cyclopean 

 eye. The infundibulum is probably what remains of the gullet of 

 the ancestors of the vertebrates. The pituitary body consists of 

 two portions, the anterior lobe, or hypophysis, derived from the 

 buccal cavity, the posterior lobe, or infundibular body, from the 

 primary fore-brain. We have already 

 spoken of the action of extracts of 

 the pituitary (p. 489). 



Functions of the Cerebellum. 

 The elaborate pattern of the 

 arbor vitas, the appearance given 

 by the branched laminae in a 

 section of the cerebellum, ex- 

 cited the speculation of the old 

 anatomists. A structure so mar- 

 vellous must be matched, they 

 thought, with functions as 

 unique. At a time when the 

 discoveries of Galvani and Volta 

 were fresh, and the world ran 

 mad on electricity, the hypo- 

 thesis of Rolando, that 'nerve- Fic.262. APURKINJE'SCELL FROM 

 force' was generated by the THE CEREBELLUM OF A CAT (AFTER 



, ,, CAJAL; GOLGI'S METHOD). 



lamellae of the cerebellum as 



electrical energy is generated by the plates of the voltaic 

 pile, ridiculous as it now appears, was not unnatural. 

 The speculation of Gall, who connected the cerebellum 

 with the development of sexual emotions and the action 

 of the generative mechanisms, was based on no fact. 

 It has been definitely disproved by the observations of 

 Luciani, who found that a bitch deprived of its cerebellum 

 showed all the phenomena of heat or ' rut,' was impregnated, 

 whelped at full term in an entirely normal manner, and 

 manifested the maternal instincts in their full intensity. 

 Flourens put forward the doctrine that the cerebellum is an 



