Miscellaneous. 323 



the opening of hundreds of stomachs will fail to find 

 food present. It is an easy disposal of the question as 

 to how each colony recognizes its native river to say 

 that 'it is instinctive.' So it is, also, when the butcher's 

 horse recognizes the familiar gates ; but we have some' 

 evidence as to what senses he uses. The fishes, prob- 

 ably prompted by functional disturbance from the 

 tumid ovaries and spermaries, are incited to movement.' 

 The courses of the sea, unmarked as they are, are, 

 within each colony's limit, their habitual pathways. An 

 unerring capacity in the fish for finding its own river 

 ma}' be no mora than that which guides the hermit- 

 crab to the shell of the natica. The latter goes to hide 

 its sensitive body, with an apparent nervous trepidation 

 at its unprotected condition. The former, with an un- 

 easiness of body from the functional changes it is 

 undergoing, is impelled to activity. The transmitted 

 habit of ascending the stream is, as it were, blended and 

 alloyed with the substance of the nerves, and, aroused 

 by its condition, carries it, without conscious purpose, 

 into the river of its progenitors and its own. The im- 

 pulses of Ihe fish are only in a slightly more compli- 

 cated series than those of the crab. That it should be 

 the instinct for a specific stream, established through 

 inheritance of many generations, is easier to under- 

 stand than that it is a sort of memory of the place of 

 its immature life, as the theory of fishculture makes it 

 and as observation seems to sustain. In the waters of 

 the Delaware, where there were no salmon originally, 

 the young salmon placed in Bushkill Creek returned 

 after five years and were taken, not only in the Dela- 

 ware River, but the larger number in the neighborhood 

 of Bushkill Creek. It is not essential that all fishes 

 should have this impelling influence, whatever it may 



