My dear Sir,

I have much pleasure in sending you a few extracts from the report of the case of hereditary blindness limited by age in the La Compte family, refer⁠⟨⁠red⁠⟩⁠ to at page 78, vol. 2, of your work— The case appears to have been first reported in the Baltimore Medical & Physical Register, 1809, and appeared in the New England Medical & Physical Journal, vol. 1, 1810, 1 pp. 39⁠⟨⁠  ⁠⟩⁠ There are some points of interest in the case beyond limitation by age.¹

⁠⟨⁠    ⁠⟩⁠ to notice that in the important section on “inheritance at corresponding periods of life”, you refer to my earlier paper but not to those which were published in 1867 “on the influence of age on hereditary disease”; & in which the subject of anticipation or postponement of hereditary ⁠⟨⁠    ⁠⟩⁠ is [superficially] discussed.² At ⁠⟨⁠the end⁠⟩⁠ of my last paper I have appended a ⁠⟨⁠    ⁠⟩⁠ soliciting cases and information for a concluding paper on atavism, which it is probable however I shall leave unwritten—³

I had the pleasure, some years ago, of becoming intimately acquainted with your friend M^r. Blyth in Calcutta, and am under great obligation to him for many past kindnesses.⁴

Among instances of reversion I have had the opportunity of becoming acquainted with the fact that the common moss ⁠⟨⁠ro⁠⟩⁠se, when transported to India, quickly loses its fringed appendages. The officers of various ships were often asked to bring out moss roses to Calcutta, but the mossy appearance soon disappeared— In like manner the descendants of spaniels of King Charles breed became long snouted & ceased to exhibit any widen⁠⟨⁠ing⁠⟩⁠ of face.

With the greatest respect, I remain, | Yours very truly | W^m Sedgwick

To Chas Darwin Esq

“Account of Hereditary Blindness, By Ennalls Martin, M.B. of Easton, Maryland.—” Baltimore Med. & Phys. Reg. 1809.—⁵

M^r. Le Compte, ancestor of this race, was a native of Picardy, in France, and married Hester D’Œtleng of Normandy. He fled to England about 160 years before this account was written, on account of the persecution of the Protestants, & afterwards emigrated to ⁠⟨⁠America⁠⟩⁠.

N⁠⟨⁠either⁠⟩⁠ he, nor his wife, nor any of their ancestors were ever known to be blind.”

“M^r. Le Compte had six children, four sons & two daughters   one of his sons, the second only named Moses, became blind, but none of his daughters … Blindness commenced in the usual manner & at the usual time of his descendants. He married after the commencement of blindness, & had eleven children, eight sons & three daughters. He lived to be 57 years of age”.

Of the sons of Moses Le Compte, six became blind, and all his daughters. Three of the blind sons and two of the daughters married and had children, which constitutes the present generation. In each family some are blind and some enjoy their sight. The ⁠⟨⁠whole⁠⟩⁠ numbers to which this calamity has extended, ⁠⟨⁠are sa⁠⟩⁠id to be thirty-seven, of which, seventeen belong to the present generation.”

Blindness, in general, begins to advance about the ⁠⟨⁠fifteenth or⁠⟩⁠ sixteenth year of age, & ends in total ⁠⟨⁠privation of⁠⟩⁠ sight about twenty-two. Previously ⁠⟨⁠to⁠⟩⁠ symptoms of blindness, there is no appearance ⁠⟨⁠of⁠⟩⁠ weakness or defect in the eyes; but as the sight declines, a hot humour, at times issues out of them. Among the first symptoms of declining sight, is a circle seen round the candle or the moon; and as the disease advances, the pupil enlarges, the cornea becomes more convex. One eye, it is said, becomes totally darkened, before sight declines in the other, but then blindness rapidly advances.”

“They are generally healthy & live to ⁠⟨⁠a considerable⁠⟩⁠ age.”

“By their intermarriage with other people, this singular peculiarity of constitution seems to weaken; and it may be hoped that a few more generations may extinguish it entirely.”

“There never has been an instance where any one of the family, who has fortunately escaped blindness, has had any blind children, or that their descendents have been subject to blindness.” (New England Med. & Phys. Journ. 1810–1–vol.1 pp. 344–8).

In the above notice the family history seems to be incorrectly given—for if, as it ⁠⟨⁠    ⁠⟩⁠ the blindness was limited to one member (Moses Le Compte) of the 1^st. generation, to 9 members in the 2^nd. ⁠⟨⁠    ⁠⟩⁠ in the 3^d., the total number of blind in the 3 generations would be 27 instead of 37.⁶ ⁠⟨⁠    ⁠⟩⁠