My dear Sir.

I ought to have written to thank you for the copy of the Third Edition of the Origin of Species which I received some months, I am ashamed to think, ago.¹ It was my Intention to read it all through before writing in acknowledgment of your kindness but as I have not quite succeeded in doing this I have determined to put off writing no longer.

I suppose you will have seen a couple of Papers on “Sexual Limitation in Hereditary Disease” in the Medico Chirurgical Review for April & July.² In case you should not, I will make an extract of the fact brought forward in that paper by Mr Sedgwick. Medico Chir. Review. April. 1861. p. 484. “M. Geschreift³ informs us that among the patients in the Eye Infirmary at Brussels were two Brothers Microphthalmic on the left side whose Father had lost his eye 15 years before his marriage in consequence of purulent ophthalmia whilst serving in the army of Holland.”

It is not as bearing upon such facts as those of Brown Séquards production of Epilepsy in the way of transmission⁴ or those of the moles suffering as you describe Page 144 from inflammation⁵ & transmitting to their offspring the condition into which they have themselves been brought that such a fact, if it be one, is of chief importance as it seems to me but as bearing upon another question, which is, Does not the nervous system and its larger appendages such as eye and ear furnish (like the shortfaced tumblers) an exception to the law of inheritance at corresponding periods of the life of parent & offspring?⁶

Sœmmering held that the human Brain attained its full size at three years of age,⁷ & this view even if not quite the truth, must shew as it was not put forth by a mere speculative man, that it is to be expected that the organ when about to be modified at all must be modified early— Again it is certain that the parts of the Brain in the Classes, Man & Ape, which are distinctively characteristic (so far as there are such parts) of the two classes are the earliest or amongst the earliest to shew themselves in the two Classes generally. Gratiolet, who has made the Convolutions his speciality, lays down in his Mémoire Sur les Plis Cerebraux, the following Rule in Italics: Les Parties qui doivent une jour dominer absolument apparaissent les premières bien que leur perfection ne s’acheve qu’après le developpement complet de tous les autres systêmes—⁸

Psychical manifestations in the offspring of both educated animals & educated men may be adduced either to shew the conformity or to prove the non conformity of the Nerve system to the usual Law—

With reference to your remarks on the rarely observed and recorded variations of internal and important organs (at pages 47 & 180) I have been watching in a great number of Insectivora & Chiroptera for variations in the number of their liver lobes. The common Plecotus Auritus has every now & then a liver just like man’s, & the hedgehog shews also occasionally a very considerable tendency to concentrate the multitudinous tongues into which its liver is divided. The Bat is a very remarkable instance as I find its multifid liver is exactly reproduced in the Vampire Phyllostoma Hastatum, and as its usual condition contrasts as strongly with that of the Vespertilio noctula as it is possible for it to do, that condition being nevertheless that of great similarity to the organ in man which every now & then the Plecotus itself also mimics—⁹ This I think bears upon what you say at Page 180.¹⁰

I must beg your pardon for writing at such length but as I have several times said on similar occasions I trust you will not take the trouble to reply to what requires no answer nor acknowledgment. Thanking you again for your sending me your Book

I am | Yours very Truly | George Rolleston—