29 



account would apply almost as well to the process in the hy- 

 dra. The tentacle which comes in contact with the prey is 

 contracted with a suddenness and vigor which belies the ap- 

 parent inertia of the moment before. The animal is seen to 

 be firmly spitted on the microscopic lances of the nemato- 

 cysts, and it is evident that the first thing that happened 

 when the animal touched the tentacle v/as the dischar^^e of 

 all the thread-cells in that region. The tentacle in con- 

 tracting carries the food, protozoan or minute woiTn or 

 whatever, towards the mouth. The long manubrium then moves 

 slightly, as if in search of the morsel. Finally, the ten- 

 tacle places the food directly upon the mouth, which pro- 

 ceeds to tux-n itself over the object and work it downwards 

 until it vanishes into the gastric pouch of the polyp. 



VII. DEGENERATION PHENOMENA . 



Owing to some peculiar condition in the water of an 

 aquarium jar, the larvae of one lot, when three months old, 

 began to exhibit most singular forms and activity. All ap- 

 pearance of the hydra was lost, ectoderm and endodei'm be- 

 came indistinguishable, and cell outlines dissolved. The 

 larvae in this condition had very much the appearance of 

 amoebae. They slumped down on the bottom of the aquarium, 



