182 THE PATH OF DEGENERATIVE EVOLUTION 



degeneration of the pineal eye in the slow-worm, 

 and in a series of lizards. 



The pineal or median eye in the slow worm and 



FIG. 61. A, Brain of a human embryo of seven weeks ; h, cerebral hemispheres; 

 ci, intermediate brain or thalarcencpphalon; cm, mid-brain ; cp, hind-brain. 



B, Brain of a human embryo about the beginning of the third month ; h, cere- 

 bral hemispheres; tg, region of the corpora quadrigemina ; cm, mid-brain. 



C, Brain of a human embryo at the middle of the third month; A, cerebral 

 hemispheres ; tq, corpora quadrigemina; ce, cerebellum. D, Human brain 

 of the fifth embryonic month ; h, cerebral hemispheres; off, olfactory lobes; 

 S, fissure of Sylvius; ce, cerebellum. (After Mihalkovics, Entwickelungs- 

 gcschichte des Gehirns. Leipzig, 1877.) 



the lizard passes through the following stages in 

 its individual development. 1 



(1) Formation of a hollow outgrowth from the 

 roof of the third ventricle of the brain 

 (fig. 62, D). 



1 P. Francotte, Reclierches sur le dtveloppement tie I'fyiphysc. 

 ( These, presentee d la Facidle de medecme de Bruxelles.} Arch, de 

 Siologie, 1888. 



