TRANSACTIONS. 



I. — On the Impregnation of the Ova of the Salmoniclce. By John 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 in a "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 Robertson 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, Avithin 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 Shaw, 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 



