DEAN, BEHAVIOR OF THE EEL DURING TRANSFORMATION 323 



September 15. The fish is now more easily seen. There is a slight 

 clouding of its transparent sides, especially near the lateral line (Fig. 3). 

 Its eyes are conspicuous and show numerous movements. It is more 

 active than in the earlier stage, sometimes swimming with broad undu- 

 lations (Fig. 4) different in type from earlier movements. A patch of 



Fig. 3. — Eel larva. September 15 



color, brownish orange, appears on the ventral body wall, just behind the 

 gill opening (jugular villi). 



. September 18. The larval length and breadth are rapidly becoming 

 reduced (Fig. 5). The caudal fin and dorsal ridge appear. The colored 

 jugular patch has now de- 

 veloped into a velvety mass 

 of lighter color, and possibly 

 serves as a larval adhesive 

 organ, which hangs freely in 

 the water. The intestine 

 can be outlined. Pigmenta- 

 tion is noted, especially 

 along the lateral line and on 

 the head-roof, and the en- 

 tire fish has a faint purplish 

 tone. It remains more often 

 at the surface than before, 

 here occasionally floating 

 and swimming on its side, 

 now and then thrusting its 

 head out of water. It remains longer in one position than heretofore. 

 If disturbed (head touched), it will wriggle its head backward, — and 

 does not initiate the backward movement from the tail as in the earliest 

 stage. 



September 19. Changes progress rapidly (Fig. 6). The coloration 

 is distinctly purple, with whitish spots near the tail, and pigment patches 

 on the ventral wall of the head and within the neural axis. Vertebra 



Fig. 4. — Eel larva. Position in swimming 



