My dear Madam

I cannot express too strongly my thanks for the extraordinary trouble which you have taken in the interesting experiment, of which you send me the result.—² I had given up all hopes of knowing whether peculiarities in the caterpillar state were hereditary, but now the point is amply proved: there is indeed a wide difference between a probability, however high & such an experiment as you have made.—

I am, also, much obliged for the information about the S. French caterpillar breeds; I was not aware the differences were so great.³

If it would not be asking too great a favour, I sh^d be greatly obliged if you would take the trouble to inform me, should you ever observe anything remarkable in the hereditary principle, or in the differences in structure or habits between breeds in the Silk-worm.— I dare not do more than hint my curiosity to know whether the Frales⁴ would prove hereditary,—ie whether it would be possible to make a breed with cocoons destitute of silk.—⁵ In the eyes of all silk-growers, this assuredly would appear the most useless of experiments ever tryed.—

Pray accept my most cordial thanks, & believe me with much respect, | Your’s sincerely obliged | C. Darwin