78 MR. HOGG OX THE MODES OF 



sed carassiis piscibus (^Cyprinus carassms, Lin.) abundantes, quum 

 ante tredecim hos annos iter per ipsnm ilium tractum, ubi jam 

 palus est, ex relatione incolarnm commodissime fieri potnerit. 

 Lacus denique recens exortos fermit initio jier aliquot annos 

 piscibus caruisse, quibus nunc abundant. Ut hoc plioenomenon 

 incola3 explicent, non illi latebras excogitant subterraneas, per 

 quas pisces ex lacu in lacum se proripere possint, sed confidenter 

 adfirmant, Mergos atque Anates ova piscium iis intulisse, ex 

 quibus proles paullatim succreverit." 



As it seems tliat the ova of the Salmon can preserve their 

 vitality at a heat not exceeding 84° of Fahrenheit, a comjDarison 

 of the temperatures of the stomachs of fish, frogs, water-newts, 

 &c., with those of water-birds, especially of the herons, ducks, 

 mergansers, and grebes, would in some degree show the possi- 

 bility of the impregnated ova being passed through the intestines, 

 without losing their productive power.*' 



And in concluding this portion of my subject, I ought to state 

 that I was not acquainted with the two last-cited authorities, at 

 the time when I penned my paper. 



Concerning the seopnd subject, or " The Modes of Fecundating 

 the Ova of the Salmonidce,'''' to be considered, I will, in the first 

 place, add the following extract from my second paper, " On the 

 Artificial Breeding of Salmon and Trout, with Eemarks on the 

 Modes of Fecundating their Ova," which I read at the meeting 

 of the Linngean Society on June 7th, 1853: — " I shall have occa- 

 sion to make a few remarks on the impregnation, or fecundation 

 of the roe of the female Salmon and Trout by the milt of the 

 males, since they necessarily arise from the observations contained 

 in the latter part of Mr. Fisher's letter, published last month in 



* Another communication, entitled—" On tlie Vitalitj' of the Ova of the Salmor.idce 

 of Different Ages," by Dr. J. Davy, which I also heard read at the meeting of the Royal 

 Society on February 7th last, described many experiments, which he had very lately 

 made on the artificially impregnated ova of the Charr caught in the river Brathay, 

 near Windermere. " From these," the Doctor asks, " may it not be considered as proved 

 that the powers of resisting an undue increase of temperature, of beai'ing distant trans- 

 port, and of retaining life in moist air, are possessed by the ova in a degree increasing 

 with age ? And may it not be concluded, that the strength of their vitality, or their 

 power of resisting unfavourable agencies, also increases with age, and foetal develop- 

 ment?" The whole letter is just published in the " Proceedings of the Royal Society," 

 No. 19, pp. 27-33, vol. viii.— (J. II., May 20, 1856.) 



