82 BLIND VERTEBRATES AND THEIR EYES. 



All the specimens of Amblyopsis from the Mitchell Caves so far examined by 

 me contained very large fatty bodies, a condition suggesting abundance of food. 

 The stomachs, as far as examined, always contained the debris of Gammarus. 

 One young Amblyopsis disappeared on the way home from the caves and had evi 

 dently been swallowed by one of the larger fish. 



The young Amblyopsis reared in the aquarium seemed to feed on the minute 

 forms found in the mud at the bottom of its aquarium. Some C&cidotea placed in 

 its aquarium soon disappeared, and the capture of one of these was noted under a 

 reading glass. The fish was quietly swimming along the side of its aquarium; 

 when it came within about an inch of the crustacean it became alert, and with the 

 next move of the Cacidotea it was captured with a very quick, well-aimed dart on 

 the part of the young fish. Others were captured while crawling along the floor of 

 the aquarium. 



Mr. Fernandus Payne has made extensive observations and experiments on the 

 feeding habits of this fish, and his notes follow : 



The following experiments have been made to determine what the blind fishes eat and more 

 especially how they detect the presence of their food. Incidentally some correlated reactions have 

 been observed. 



In the laboratory, after the fishes had become accustomed to their new conditions, I had no 

 trouble in getting them to eat isopods, amphipods, young crawfish, and diptera and salamander 

 larvEe. They will also take meat from the end of a thread when it is moved about in front of them 

 or brought in contact with the body. The meat, in nearly all cases, is ejected either before or after 

 it has been swallowed. From these observations it seems that they will eat any small animal which 

 moves about in the water. According to my experiments they prefer amphipods. This may be due 

 to the fact that they are more active than the other animals, and hence their presence is more easily 

 detected. If isopods and amphipods are placed in the same aquarium, the amphipods are eaten 

 first. The young of 25 cm. in length readily eat cyclops, daphnids, and aquatic fly larvae. I have 

 seen them eat fly larvae until the stomach was so full that they had difficulty in keeping the larvae 

 from wriggling out again. 



In the caves both variety and quantity of food are limited. Crangonyx and Caddotea appear in 

 considerable numbers, but most of them seem to stay under rocks in running water while the fishes 

 are confined to the quiet pools. Young crawfish are certainly not plentiful, for the adults are not 

 very numerous. Whether Cyclops or any other small Crustacea are present in any abundance, I 

 am unable to say. I know of nothing else on which the young blind fishes could feed. In July, 

 1906, 1 took a number of young from the gill cavity of the mother, put them into a box made of cheese- 

 cloth and sunk the box in a quiet pool of water in the cave. They remained in this place for about a 

 month and were growing nicely. I have no doubt they would have lived here much longer had not 

 the cloth become full of holes and freed them. I put no food into the box, so they must have eaten 

 the small organisms in the water. 



Fishes must find their food either by the sense of sight, taste, touch, or smell, or by a combination 

 of two or more of these. In most fishes sight undoubtedly plays the predominant part in locat- 

 ing and seizing food. This factor is excluded in Amblyopsis. Herrick has given some excellent 

 experiments bearing upon this question. He finds that practically the whole cutaneous surface of 

 Ainciimis is sensitive to both tactile and gustatory stimuli, but that the gustatory stimuli are of the 

 greatest value 1" the cat-fish in procuring food. The hake (Urophycis tennis) catches its food by 

 sight, only when the food is in motion. Bits of meat, etc., lying on the bottom are usually found by 

 the aid of the free ventral fins. From these and other experiments, Herrick concludes that the hake 

 receives both tactile and gustatory stimuli by means of the free fin-rays and to some extent, doubtless, 

 by other parts of the outer body surface. He was unable to determine whether or not smell played 

 any part. When food is thrown into the aquarium the tomcod (Microgadus tomcod) catches it while 

 it is falling through the water. The ventral fins are used in locating sapid substances lying on the 

 bottom. He cut the olfat lory nerves to see whether smell played any part in the detection of food 

 and found that the fishes with the nerves cut acted in every respect like normal fishes. The sea 



