THE PINEAL BODY 155 



8. Lanius excubitor. Studnicka ('96). 386 In this species the 

 epiphysis is saccular. 



9. Turdus pilaris. Studnicka ('96). 386 The epiphysis is follic- 

 ular in this form. 



10. Coccothraustes vulgaris. Studnicka ('96). 386 In this 

 species the epiphysis is hollow and saccular in its entire extent. 



11. Passer domesiicus. Gage ('95). 136 The epiphysis is 

 hollow and saccular in this form. 



In birds, as in ophidians, the evidence of the glandular nature 

 of the epiphysis is pronounced. Every form examined yields 

 many suggestive indications that the pineal body in birds is a 

 glandular organ. The element pertaining to the parietal eye 

 has not been observed in the avian forms examined and the 

 epiphysis is evidently the highly specialized proximal portion of 

 the pineal organ. The stalk and end-vesicle have disappeared. 

 The element referred to in birds as the stalk is something entirely 

 different from that portion of the lower forms which connects 

 the proximal portion and the end-vesicle. The avian stalk is a 

 secondary development consequent upon the marked enlarge- 

 ment and solidification of the proximal portion. During this 

 process the pineal body tends to move slightly away from the 

 roof, and in so doing produces an elongation in the originally 

 constricted area which connects the epiphysis with the roof of 

 the interbrain. This, in contradistinction to the stalk of the 

 end- vesicle, is the stalk or peduncle of the epiphysis. The pineal 

 recess contained within this peduncle is not entirely homologous 

 with the pineal recess of the lower forms, for in the latter in- 

 stances the recess extends into the proximal portion its entire 

 length, while in birds it is restricted to the peduncle. 



8. Comparative anatomy and histology of the epiphyseal complex 



in mammals 



In mammals the only element of the epiphyseal complex 

 which persists is the proximal portion of the pineal organ. In 

 but a single instance thus far recorded is there evidence of the 

 parapineal element, i.e., Cutore's 74 observation of a small anterior 



