TRANSACTIONS. 
I.—On the Impregnation of the Ova of the Salmonide. By Joun Davy, M.D., 
F.R.S. Lond. & Edin., Inspector-General of Army Hospitals. 
(Read 6th March 1854.) 
From time to time it has been asserted, that the function of impregnation of 
the ova of these fish is performed after the manner of that of the cartilaginous, 
viz., before exclusion. The instances related in proof are commonly of a vague 
kind, and such that little credit can be attached to them. Recently a more precise 
example has been adduced,—how the ova of the trout, taken from the abdomen of 
the parent fish, and placed ina “running stream” apart, included in a perforated 
box, in due time were hatched, producing young fish. The particulars of the 
experiment, and the result, were published in the spring of last year, and in more 
than one of the provincial papers; and Dr Rosertson of Dunkeld was named as 
the institutor and reporter of the trial. 
Considering the manner in which this statement was made and received, and 
the practical conclusion deduced,—that no longer any trouble need be taken in 
the artificial mode of breeding to obtain the milt to apply to the roe, I have 
thought it worth while to give the subject some attention, on the supposition that 
the result, as stated, may have been accurate, being, as it appeared to me 
to be, within the limits of possibility,—though I cannot say, keeping in mind 
the structure of the male and female fish, and all the information hitherto col- 
lected respecting the manner in which the generative process is carried on by 
them,-—that it is within the limits of probability. 
I shall first briefly notice some trials which have been made, and with a view 
to determine the question. 
Mr Suaw, in his valuable paper on the Development and Growth of Salmon 
Fry, published in 1840 in the Transactions of this Society, describes how, in two 
instances, he obtained negative results in experiments on mature ova of the sal- 
VOL. XXI. PART I. A 
