On the Growth of the Salmon. tOt 



ed ; and tlieir procreative powers afford an additional confirmtu- 

 tion of tlieir being identical. Mr Shaw moreover observes, tha^ 

 if tlie parr were a distinct species, the results of their attendance 

 on the female salmon wonld produce universal confusion among the 

 migratory inhabitants of rivers, " from the circumstance of the male 

 parrs, in" a breeding state, occupying in great numbers the very 

 centre of the salmon spawning-bed ; while the female salmon her- 

 self is, at the same instant, pouring thousands of her ova into the 

 very spot where they are thus genially congregated/' 



Mr Shaw's experiments were conducted with great care; have 

 been frequently verified by repetition ; and have always been fol- 

 lowed by the same results. He concludes his paper by stating, that 

 so far as his own observations extend, the trough, or special spawn- 

 ing-bed, is excavated by the female alone, and by means of a pecu- 

 liar action of the tail. The belief hitherto entertained has been, 

 that she was greatly aided in tliis removal and replacing of the 

 gravel by the snout and under jaw of the male. The process of 

 laying usually occupies three or four days. He found in the course 

 of his experiments, that the death of the female did not (at least 

 within a short time) destroy the vitality of the spawn, or its recep- 

 tive power of fecundation. He impregnated ova from the body of 

 a fish which had been dead for nearly two hours, with the milt of a 

 living parr, and vivification followed in the usual course. 



[In reference to the preceding abstract of Mr ShaWs interesting and im- 

 portant observations on salmon ft-y, we shall here merely remind the reader, 

 that this ingenious inquii-er's earlier experiments -were first communicated 

 to the public through the medium of our own Journal. See Edln. Neic Phil. 

 Journ. for July 1836, vol. xxi p. 99, and for January 1838, vol. xxiv. p. 165. 

 We shall present a consecutive view of the whole subject (with an illustra- 

 tive plate), in our next number. Meanwhile, we may state m addition to 

 the points glanced at in the above abstract, that as it had been objected to 

 Mr bhaw's practice in reference to the mechanical mode of impregnation, 

 that the generative influence might have been in some other way effected 

 than through the medium of the parr, he therefore took every means to prove 

 the truthful results of his experiments, by varying in some measure their 

 conditions. Thus, in two instances, he took a portion of the ova from a fe- 

 male salmon, and placed it, inthout Imprenmtion, in a stream of pure water. 

 The result was as he anticipated : up to the termination of the general 

 hatching season no appearance of vitality was ever manifested. The females 

 were the same individuals with which the parrs wore made to spawn, as 

 above mentioned, but to avoid contact, the unimpregnated lots were m each 

 case taken first, and removed to a distance. The trough or spawning-bed, Mr 

 Sliaw observes, is formed by the female fish without the assistance of the 

 male, and not by means of the snout, as usually supposed, but of the caudal 

 extremity. This last observation, we may note, had been previously made 

 by Mr Potts of Berwick, in the course of his correspondence with Pennant. 

 — EniT. Phil. Jouun.] 



2. On the use of the word "Temperature" in the Analytical 

 Theory of Heat. By Professor Kelland. 



A third communication by Professor Forbes, " On the in- 

 fluence of the Mechanical Textiirt! of Screens on the imme-* 



