90 CASWELL GRAVE 



3. The lenses of the eye are not modified retinal cells, but are 

 deposition products of a semiliquid or gelatinous nature, formed 

 within vacuoles of cells located in the margin of the ret- 

 inal ganglion. 



4. Visual rods, differentiated in retinal cells of the eye, pro- 

 ject through the pigment zone and end at the inner surface of 

 the pigment cup. 



5. The eye is proved, by structural and physiological evidence, 

 to function in the orienting responses of the tadpole to light. 



6. The statolith is formed in a vacuole of the sensory statolith- 

 cell and is composed of a hard substance that is not disintegrated 

 by strong acids. 



7. A visceral nerve, which originates in the visceral ganglion 

 and has a distribution in the region of the endostyle, is described. 



8. The nerve cord is not dorsal in position, but, due to a perma- 

 nent twist of the tail 90° to the left, is located on the left side 

 of the notocord. 



9. The two series of muscle cells located on the dorsal and 

 ventral sides of the notocord are shown by morphological and 

 physiological evidence to function as units in a way to produce 

 the rotatory movement of the body during locomotion. 



