PLATE 1 



EXPLANATION OF FIGURES 



63 Photomicrograph of a transverse section through the eyes and forebrain 

 of the embryo in figure 3. fhr., unilobed small forebrain; o.p., fused olfactor}^ 

 pit. X 116. 



64 Photomicrograph of a more posterior section (region of optic lobes) of 

 the same embryo, o.l., optic lobes; o.c, optic cross. X 116. 



65 Photomicrograph of a transverse section through the eye of the Cyclopean 

 embryo in figure 5. o.l., optic lobes. X 135. 



66 Photomicrograph of a transverse section through the eye of the cyclopean 

 embryo in figure 12. /6?\, forebrain; o.c./., blastolytic optic cup fragment. X 116 



67 A more posterior section (midbrain) of the same embryo, to demonstrate 

 the large size of the fused eye and the small size of the defective midbrain, mb., 

 midbrain; e.c, ear cartilage; m., mouth. X 116. 



68 Photomicrograph of a transverse section through the anterior part of the 

 eye of the cyclopean embryo in figure 6. p., pigment epithelium, r.c, rods and 

 cones; o.p., olfactory pit; br., brain. X 116. 



69 A more posterior section through embr3'o in figure 6. ni,.o., medulla ob- 

 longata; oe., oedema; pi., plasma of pericardium, into which the ej^e dips; p., 

 pigment epithelium; r., retina. X 116. 



70 Photomicrograph of a transverse section through the eye of the cyclopean 

 embryo in figure 8, fbr., forebrain; //., yolk. X 116. 



574 



