294 THE PINEAL ORGAN 



Cameron was unable to find distinct evidence of fibres passing from the 

 superior commissure to the epiphysis in chick embryos, and concluded 

 that if they do exist they must be very scanty, but in the blenny, Zoarces 

 vivipara, he described and figured a bundle of nerve-fibres passing from 

 the upper part of the superior commissure some of which ended in the 

 epiphysial segment of the same side, while others, decussating, crossed 

 to the epiphysial segment of the opposite side (Fig. 201). He also pub- 

 lished photographs of sagittal and horizontal sections through the superior 



Fig. 201. — Transverse Section through the Ganglia Habenulai and 

 Epiphyseal Elements of an Embryo Blenny (Zoarces vivipara) showing 

 Decussation of the Upper Fibres of the Superior Commissure. (After 

 Cameron, 1904.) 

 C. Hab. : commissura habenularis. G. Hb. D. : right ganglion habenuke. 

 Ep. D. : right epiphyseal element. G. Hb. S. : left ganglion habenulae. 



Ep. S. : left epiphyseal element. 



commissure in the adult human subject, prepared by the Weigert-Pal 

 method, and showing the same division of the habenular commissure into 

 an upper and lower segment, the former sending decussating fibres into 

 the pineal body, the lower and posterior segment being composed of 

 commissural fibres between the two habenular ganglia and of fibres 

 joining the striae medullares. 



Structure and Contents of the Adult Pineal Organ of Birds 



Three different types of pineal organ were described by Studnicka : 



1 . Simple tubular. 



2. Follicular. 



3. Solid lobular. 



1 . The simple tubular type is further subdivided into : 



(a) Epiphyses with thin walls. 



(b) Epiphyses with thick walls. 



The first (Fig. 199) is exemplified by the pineal organ of the sparrow, 

 which has an elongated tubular epiphysis ending in a small lobulated 

 vesicle. It lies immediately in front of the cerebellum, between the 



