INHERITANCE OF ACQUIRED CHARACTERS 209 



ence is one due to the environment of the in(Hvidual. Those 

 in the sea find adequate sahs from wliieli to devehip tlicir 

 coats of mail. Those in fresh water do not find this, while 

 those in river mouths and otlier Ijraokish situations develop 

 armature in intermediate degrees. In the genus Kucnlia, a 

 sticklel)ack confined to fresh waters of the Middle A\'estern 

 States, plates are never developed. 



The Loch Leven trout, Salmo levenensis, is distinguished 

 from the brook trout of England, Salmo eriox {jario), in its 

 native waters by certain o])vious characters. These disappear 

 when the eggs are planted in brooks in England or in Cahfornia, 

 and the species develops as the common English brook trout. 

 But it is conceivable that the obvious or ontogenetic traits of 

 the Loch Leven trout are not the real or phylogenetic distinc- 

 tions, and that the latter, more subtle, engendered through in- 

 dividual variation, inheritance, selection, and isolation, really 

 exist, although they have escaped the attention of iclithy- 

 ologists. 



After the Loch Leven trout was planted in the Yosemite 

 Park in 1896, it remained for nine years unnoticed. In 19U5 

 individuals sent to Stanford University wef^, so far as could 

 be seen, exactly like English brook trout. But it is conceivable 

 that differences in food and water have caused slight ontogenetic 

 distinctions. It is certain that in isolation from all parent 

 stocks they will in time develop larger differences which, after 

 many thousand generations, will be specific or subspecific. At 

 present, these trout are quite unlike the native rainbow trout 

 {Salmo irideus gilherti) of the Yosemite. The ontogenetic char- 

 acters will perhaps approach those of the latter, but the phylo- 

 genetic movement may be in quite another direction. 



Another ontogenetic species is the little char or trout {Sal- 

 velinus tudes Cope) from Unalaska. In Captain's Harbor, Una- 

 laska, the Dolly Varden trout, Salveliiius malma, swarms in 

 myriads, in fresh and salt water alike, reaching in the sea a 

 weight of from six to twelve pounds. A little oj)en brook, whicli 

 drops into the harbor by an impassable waterfall, contains also 

 an abundance of Dolly Varden trout, mature at six inches and 

 weighing but a few ounces. This is Salvelinus tudcfi. In the 

 harbor the trout are gray with lighter gray sjiots, and fins scarcely 

 rosy. In the brook, the trout are steel blue, with crimson spots 

 and orange fins, striped with white and black. In all visible 



