To J. J. Weir   17 March [1870]

My dear Sir

It is my decided opinion that you ought to send an account to some Sci Soc^y. & I think to the Royal Soc^y.— I w^d. communicate it, if you so decide.—¹ You might give as a preliminary reason the publication in the Transat^s. of the celebrated Morton case & the Pig case by M^r Giles..—² You might also allude to the evident physiological importance of such facts, as bearing on the theory of Generation: whether it w^d be prudent to allude to despised Pangenesis, I cannot say; but I fully believe Pan: will have its successful day.— Pray ascertain carefully the colour of the dam & sire.— see about duns in my Book. vol I p. 55³ The extension of the mane & the form of hoofs are grand new facts.— Is the hair of your horse at all curly: for observe case given by me Vol. 2. p. 325, from Azara of correlation of form of hoof with curly hair?—⁴ See, also, in my Book; Vol I p. 55. Vol. 2. p 41 how excessively rare stripes are on faces of horses in England.— Give age of your Horse.—

You are aware that D^r Carpenter & others have tried to account for the effect of a first impregnation, from the influence of the blood of the crossed embryo;⁵ but with Physiologists who believe that the reproductive elements are actually formed by the reproductive glands this view is inconsistent.— Pray look at what I have said in Dom: Animals. Vol. I p. 402–405. Against this doctrine: it seems to me more probable that the gemmules affect the ovaria alone.— I remember formerly speculating, like you, on the assertion that wives grow like their husbands; but how impossible to eliminate effect of imitation & same habits of life &c.— Your letter has interested me profoundly.

In Haste. | Very sincerely your’s | Ch Darwin

PS. Since publishing I have heard of additional cases—very good one in regard to Westphalian pigs crossed by English boar, & all subsequent offspring affected given in Illust: landwirth: Zeitung 1868 p. 143.⁶

I have shown that mules are often striped though neither parent may be striped, due to ancient reversion— Now Fritz Müller writes to me from S. Brazil “I have been assured by persons who certainly never had heard of L^d. Morton’s mare, that mares which have borne hybrids to an ass, are particularly liable to produce afterwards striped ass-colts.”⁷ So a previous fertilisation apparently gives to the subsequent offspring a tendency to certain characters, as well as characters actually possessed by the first male.—

In the Reprint, (not called a 2^d Edition) of my Domestic Animals, I give good additional case of subsequent progeny of Hairless dog, being hairy, from effects of first impregnation.—⁸

P.S. 2^d.

The suggestion no doubt is superfluous, but you ought, I think, to measure extension of mane beyond a line joining front or back of ears & compare with horse.

Also to measure (& give comparison with horse) length, breadth & depth of Hoofs.—