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Darwin Correspondence Project

From F. Bashford and Edward Blyth   [after 3 July 1855]1

Facts on the interbreeding of different races of Silkworms, by F. Bashford Esq, of Surdah Factory, Lower Bengal. N.B. Mr. Bashford is now in England, & I do not know his address; but he went home in the ‘Alfred’, which fact may lead to your discovery of it. EB.2

I imported some Silk worms’ Eggs from China & France, to cross & improve the Madrassee breed in India. the French Eggs hatched, & the Cocoons I got were as good as the originals in France, & of the same color—yellow

French & China worms are annuals, our Bengal Madrassee monthly—

The China Eggs hatched, theengal Madrassee monthly—

The China Eggs hatched, the worms were small, & Cocoons small, & of a white color, I have no idea what their originals were. I procured both Male & Female of our Bengal Yellow Madrassee Cocoons, the race is not indigenous, but originally imported, it is supposed & I selected them in consequence, fancying the cross would succeed better than with a pure race. they joined readily with the French & China French Males to Bengal Females, & Bengal (Madrassee) Males to French Females— the Eggs were laid in due course, those of the French Male, & Madrassee Female, (the usual size of Bengal Eggs) remained Yellow in color till two or three days before hatching (about 7 days) when a little black speck was observable, the next & following day, they became all dark, & immediately hatched—

The Eggs from the French Female & Bengal Madrassee Male large in size as in France, were yellow also on first being deposited—but remained so for about 2 days only, when they changed to a dark slate color, similar nearly to the color of the Eggs I imported, & they have remained so ever since, about a month, this leads me to fancy the cross has not altered their nature, & that they will not hatch till the usual period with French Eggs in France, a year after—

The Cocoons I have got from the Cross between the French Male & Bengal female, are in appearance very like the original French exactly so in color, & nearly as good in quality— I have no Eggs from this cross as yet.

The China Female & Madrassee Male gave Eggs about the size of the Madrassee, they turned dark on 2nd. & 3rd. day, & remain so now—

The China Male & Bengal Female, gave Eggs & produced in the same way as the French Male, but have given Cocoons quite opposite in color, viz. yellow, & about double the size of the originals— they have eaten out, & the Moths are more than double the size of their Parents, & very strong— I have Eggs from this cross, & they have turned dark in the same way, as did the China Female with the Madrassee Male, which makes me fear that the hatching will not take place on 8th or 10th day—as with their Parents’ Eggs—& that the worm will again assimilate, & fall into the Nature of the China, & my endeavour to alter them to our Bengal nature & habits will have failed— The Cocoons from the China cross are pointed at one end, very different from the originals. The French Cocoons were yellow, & so were the Madrassee I crossed with, but the China were all white— My sole object in importing French & China Eggs is to engraft a better race, or rather give vigor to our degenerated Madrassee stock, but still to retain so far the nature of the Madrassee, as to produce every month. An annual worm is of no advantage to a country where Mulberry is procurable at all times— in cold climates they are obliged to regulate their worms, according to the supply of food—

CD annotations

‘Blyth’s Notes’3 added pencil
4.7 French Male, & Madrassee Female, 4.8] ‘1’ added pencil
5.1 French Female … Madrassee Male] ‘2’ added pencil
‘The Hybrids were they fertile?’added pencil
7.1 The China Female & Madrassee Male] ‘3’ added pencil
8.1 The China Male & Bengal Female] ‘4’ added pencil
8.1 same way] ‘ie in 10 days’ added pencil
double scored pencil; ‘both parents?’added pencil
8.5 cross,] ‘hybrid’ interl pencil before
8.5 China Female] ‘3’ added pencil
scored pencil; ‘both?’interl pencil before ‘originals’
End of letter: ‘Whether several generations of Hybrids; whether they have kept constant; whether fertile; whether all hybrids from same cross alike.— | Selection? | Hereditary?’ pencil


Dated by Blyth’s reference at the top of the letter to Bashford’s arrival in England via the Alfred. The Alfred arrived at Gravesend on 3 July 1855 (The Times, 4 July 1855, p. 12).
Blyth forwarded Bashford’s letter to CD adding this explanatory note at the top of the letter.
Bashford’s letter had evidently been pinned to other notes and memoranda from Blyth.


Notes on the interbreeding of different races of silkworm. [Forwarded with explanatory note by Edward Blyth.]

Letter details

Letter no.
Frederick Bashford; Edward Blyth
Charles Robert Darwin
Sent from
Source of text
DAR 98: A56
Physical description
Amem 2pp †, † (by Edward Blyth)

Please cite as

Darwin Correspondence Project, “Letter no. 1690,” accessed on 24 May 2022,

Also published in The Correspondence of Charles Darwin, vol. 5