PINEAL AND PITUITARY BODIES OF THE BRAIN. 19 
dorsal surface of the brain developes into a vesicular distal 
and a stalk-like proximal portion, and that in some forms 
the distal part is converted into a remarkable structure 
resembling a sense-organ. ‘This he found in its most 
developed condition in the Lacertilian Anguis fragilis 
where the parietal foramen in the roof of the skull is 
occupied by the rounded distal portion of the epiphysis 
in a form which he compares with a highly developed 
invertebrate eye, such as that of the higher Mollusca. 
De Graaf further suggests that in the lower vertebrates of 
former times, such as the Labyrinthodonts, the pineal eye 
may have played an important part as a sense-organ. 
Shortly after the appearance of De Graaf’s paper, 
W. Baldwin Spencer, now Professor of Biology at 
Melbourne, published a preliminary account* of his 
independent investigations into the structure of the pineal 
eye in some Lizards. This paper confirmed De Graaf’s 
results, and treated specially of the condition of the 
epiphysis in Hatteria punctata, in which Spencer found 
the sense-organ in even a more highly developed and 
more interesting condition than in the case of the forms 
described by De Graaf. 
_ A few months later, Spencer published a detailed 
memoir,}+ describing minutely the structure of the pineal 
sense-organ in a number of the Lacertilia, and comparing 
it with other sense-organs in Vertebrata and Invertebrata. 
In Hatteria punctata he found that the proximal portion 
of the epiphysis becomes converted into a nerve (PI. I., 
fig. 3, n.), leading from the brain to the vesicular distal 
portion, which is modified into an eye-like structure lying 
imbedded in connective tissue in the parietal foramen. 
ii Nature, vol, xxxiv., p. 33, 18th May, 1886. 
+ ‘‘On the Presence and Structure of the Pineal Eye in Lacertilia,” 
Quarterly Journal of Microscopical Science for October, 1886, p. 165. 
2—2 
