Sargemt. — Optic Reflex Apparatus. 



PLATE 5. 



Figs. 32-34. Amia calva, 8th day. Three successive sagittal sections of the an- 

 terior portion of the mesenccphiUon, showing the optic reflex cells 

 and their axons uniting witliin tlie inesocoele to form the fibre of Reiss- 

 ner. Figure 32 is median. In tiiese figures anterior is at the right, and 

 dorsal is toward the upper left-hand corner of the plate. X 205. 



Fig. 35. Ainia calva, 17th day. Sagittal section of the anterior portion of the 

 mesencephalon, anterior at left. The system of axons within the 

 mesocoele is somewhat more consolidated. X 205. 



Fig. 36. Amia calva, 5tii day. Transverse section through the roof of the mesen- 

 cephalon, eaudad of the posterior commissure, showing the optic reflex 

 cells. X 100. 



Fig. 37. Amia calva, 5th day Transverse section through the roof of tlie mesen- 

 cephalon, and edge of the posterior commissure flexure, sliowing the 

 recessus of mesocoele al)ove the posterior commissure. X 87. 



Fig. 88. Amia calva, 8th day. Transverse section thnmgli anterior portion of 

 the mesencephalon and jiosterior commissure, anterior to preceding. 

 X 120. 



Fig. 30. Amia calva, 4th day Sagittal section througii the posterior portion of 

 the cord, showing a single posterior canal-cell and its axon. X 1200. 



