I. On the vitality of the ova of the salmonidæ of different ages; in a letter addressed to Charles Darwin, Esq., M. A., V. P. R. S. &c
My dear Sir,—In a letter which I had the honour to address to you last year "On the Ova of the Salmon in relation to the distribution of Species,” I have expressed the hope that some of the results of observations therein described may aid in solving the question as to the period, the age, at which the impregnated ova of fish are most retentive of life, and consequently are in the state best fitted for transport without loss of life. Joining with you in considering the subject in need of and deserving further inquiry, I have taken the earliest opportunity that has offered of resuming it. The experiments which I have made, and which I shall now describe, have been more limited than I could have wished, having been confined to the ova of the Charr, as I was not able to obtain the ova of the Salmon or any of its congeners in a fit state for the trials required.