84 MR. HOGG ON THE MODES OF 



spawning described by Mr. Ellis, in his ' Natural History of the 

 Salmon,^ from which it would appear that the male and female 

 fishes having jointly made a furrow in the gravel, place them- 

 selves one on each side of it, and throwing themselves on their 

 sides, ' again come together, and rubbing against each other, both 

 shed their spawn into the furrow at the same time. Tliis pro- 

 cess is not completed at once ; it requires from eight to twelve 

 days for them to lay all their spawn.' Mr. Hogg argues from 

 this description, that it is possible that the female trout from 

 which Dr. Robertson took the ova might have gone through this 

 process with the male, and might have thus received the fecun- 

 dating influence, just before she was caught ; but on this solution 

 he does not rely. He thinks it more probable, that in the running 

 stream, in which the perforated zinc box was placed, there were 

 some male trouts, which had deposited their milt near the box, 

 and that some of the 7nilt might have been carried ivith the stream 

 through the holes of the box, and have so fecundated the ova 

 within it." 



And the third report — ^which is exactly the same as the second 

 contained in the " Proceedings of the Linnaean Society," was pub- 

 lished in the December number, 1853, of the " Annals and 

 Magazine of Natural History," vol. xii. (2nd series), ]). 472. 



Dr. John Davy, in a paper dated Jan. 4, 1854, which was 

 read to the Royal Society of Edinburgh, on March 6th following, 

 and published in the Tixmsactions of that Society (pp. 1-5, vol. 

 21, part i., for 1854), brings forward some of the same views, 

 and comes to the like conclusions, which I had previously enter- 

 tained and arrived at, and which are detailed in the extracts from 

 my own paper already annexed. Dr. Davy's paper is entitled — 

 " On the Impregnation of the Ova of the Salmonidce ;" and from 

 it I will here quote certain passages relating to our common 

 subject. 



" Recently, a precise example has been adduced, how the ova 

 of the Trout, taken from the abdomen of the parent fish, and 

 placed in a 'running stream' apart, included in a perforated 

 box, in due time were hatched, producing young fish. The par- 

 ticulars of the experiment, and the result, were published in the 



