134 Fresh Water Aquarium 



for the mating time by changing these colors 

 for a most gorgeous wedding dress of all 

 shades of the rainbow, blended into a very 

 beautiful ensemble. This coloring even af- 

 fects the eye of the fish, where it manifests 

 itself in a reddish tint. While the female 

 fish retains its usual color, it develops, at 

 spawning time, a pinkish ovipositor which 

 hangs down to a length of about one inch. 

 This organ, unusual in fishes, has a special 

 function in the propagation of the bitterling. 

 While it is not unusual for lower members 

 of the animal kingdom or for fungi to re- 

 quire one or more hosts of a different 

 family than their own, in order to reach a 

 state of perfect development, it is indeed 

 strange in beings so highly organized as 

 fishes ; yet such is here the case. The ovipos- 

 itor serves for nothing less than to insert 

 the eggs into the interior of a fresh water 

 mussel, — Unto. To do this the fishes have 

 to await the moment when the mussel opens 

 to take in water, whereupon the female in- 



