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Darwin Correspondence Project

From James Torbitt   4 November 1879

Belfast

4th Novr 1879

Charles Darwin Esqr. | Down, Beckenham, Kent.

My dear Sir,

I have all along been most anxious to spare your time and therefore have not till now replied to your letter of 20th. Septr. last, one of the kindest possible and most highly valued.1

With regard to “Black ’75”—best thanks for your trouble in growing it and reporting on its behaviour.2 No 1 was the part of the variety which came true to the original type. No. 2 which by some mistake I have called, it seems, the “variety” was that part of the variety which came untrue; and I now suspect that the malady under which it suffers was caused by slugs partially cutting through the stems during the year 1878, instances of which I have observed. I have sent part of this variety to Paris, requesting them to grow a few tubers of it year by year to see what becomes of it; this they promise to do, and to report results.

There were few humble bees here and I did not observe one visiting the flowers of the potato, but the flowers had little or no perfume this year, and almost all dropped off.

On yesterday I received the last lots of the new varieties, and also your valued letter of 1st. Inst.3 before replying to which I wished to have a nights consideration—after which, “I have now to say, that in so far as my judgment goes, complete success is not only fairly hopeful, but complete success has been obtained. I have no doubt whatever, that by means of cross-fertilization and selection, any number of varieties of the potato can be produced fungus-proof not only in the tuber, but also in the foliage”—the statement in my last respects, that the whole of the foliage of the seedlings of present year was destroyed by the parasite was a mistake.4

As to costs of experiments; should it be determined on to hold the whole of the valuable varieties for another year, I think about four or five hundred pounds would be requisite, and should trade come right before March next I should be prepared to incur that expenditure myself; should trade not come right I will be prepared to do exactly whatever you, my dear Sir may wish; but by getting rid of the potatoes and continuing the cross-breeding no further money would be needed, and I intend to continue the crossing so long as I am able.

I did not publish any thing this year, except a letter to the “Field” in February last, which I did not trouble you with, but now enclose marking in red some parts you might wish to read.5

In a few days I hope to make inspection of the whole of the varieties, and to submit a detailed report of all the facts I have observed.

I am my dear Sir | most respectfully yours | James Torbitt

[Enclosure]

FROM “THE FIELD.”

CULTIVATION OF THE POTATO.

Sir— Mr. Darwin authorises me to state, that “after due consideration of the information which I communicated to him, he fully approves of the principles on which I have been acting in this matter”—namely, growing the plant from the largest and heaviest seed, and selecting for continuous propagation by their buds (sets) those plants which proved themselves most vigorous and least subject to the Disease. And before the publication of his work on “Cross-Fertilization of Plants,” he did me the great honour to explain that the advantages to be obtained by the crossing of plants were similar to those which have been obtained by the cross-breeding of animals; and suggested that to the principle of “selection of the fittest” I should add the increased vigour of life, and the other advantages to be obtained by cross-fertilization—cross-breeding carried down through successive generations.6 This suggestion I have been acting on to the best of my ability; and with Mr. Darwin’s approval I now beg leave to submit to you an account of the progress of the work, so far as it has gone.

At the Meeting of the British Association at Belfast, in the Summer of 1874, I advocated the propriety of instituting such experiments:7 the result of the discussion being that I determined to make them myself, and on an extensive scale; to attempt, in fact, to introduce a rational system of cultivation of the plant to these kingdoms, and to the world at large.

Consequently, in the succeeding Autumn I advertised for berries of the plant, obtained a couple of tons, saved the seed, and in the Spring of 1875 I sent ten thousand seeds—ten thousand new distinct varieties of the plant—with instructions how to grow them, to each Member of the House of Lords, each Member of the House of Commons, each Magistrate of Ulster, and to some hundreds of persons interested, whose names I had obtained by advertising. I do not know the number of people so supplied with seeds, but it was large, seeing that the extraction of the addresses from the directories and writing them on the envelopes occupied a clerk for ten days. This distribution of seed I repeated in the Spring of 1876; but my efforts in that direction failed, for I have had no reports from the public of any particular value.

This want of success on the part of the public I attribute to two causes:—

First—Where the seeds were grown at all, the Gardeners in most cases, I suspect, failed to see that each seed is a distinct variety; they mixed the produce of the seeds—put together, for instance, all white tubers of a kidney shape—and where that has been done the result is of no value, because such mixtures contain the worst as well as the best varieties.

Second—The old varieties of the plant do not produce seed, and the seed I obtained by advertisement, besides being self-fertilized, was from new coarse varieties, the tubers produced thereby being generally of uncouth shapes, and, seemingly, unworthy of cultivation, and therefore not further cultivated.

My own experience is as follows:—

In the Spring of 1875 I selected a field the most suitable I could find for the Parisite, whose growth in the body of the plant constitutes the Disease.8

In the Summer I planted out into this field five thousand Potato plants, selected best of some one hundred thousand grown from seed, sown under glass in the Spring. When raising them in the Autumn I found that many had produced no tubers at all; many had had all their tubers destroyed by the Disease; a great proportion was more or less diseased; a few were absolutely free from disease; and almost all were of uncouth shapes. Of these five thousand plants I selected about a thousand of the best, and stored them over; in the Spring I found that about one-half of them had become considerably diseased, and these I destroyed; the remaining five hundred varieties I planted in the Spring of 1876 in a field which had not been broken up for twenty or thirty years, and they grew most luxuriantly: when in bloom, they resembled an immense bed of flowers. On raising them in the Autumn I found the yield very much larger than usual, and a further number of varieties diseased, which I destroyed, storing over the remainder.

In the Spring of 1877 I found further numbers of varieties diseased; destroyed them, and planted the remaining varieties,—this time as a crop in common rotation—and the growth was again most luxuriant, the large white flowers of certain varieties seeming to sparkle in the sunlight, and the yield being as before—very much larger than usual. Again, further varieties had become diseased; were destroyed; and remainder stored over, more varieties becoming diseased during the Winter, which were destroyed. In the Spring of 1878 I planted the remaining varieties—some fifty or sixty, perhaps—in the usual way, and a most remarkable change in their lives occurred: the beautiful bloom almost disappeared; such flowers as they produced were smaller, and some had changed colour; the foliage also had changed slightly; but the yield was as previously—very large. The proportion of diseased tubers in these selected best 1875 varieties I find at present to range from two or so to as much as ten or twelve per cent.; and there are three of them absolutely free from disease, and have been so during each year of their lives. Also, I suspect—in fact I have no doubt, merely from eating of them—that all these new varieties, besides being much more prolific, are much more nutritive than the old varieties, contain more flesh-forming matter in proportion to the starch; and the conclusion I draw from the foregoing facts is, that new varieties of the plant may easily be obtained, which, during the first few years of life, will be so prolific and so little subject to the Disease that they will give, after separating the diseased tubers, a larger yield of sound tubers than the old varieties give of sound and diseased tubers put together.

As regards the cross-breeds—

The first cross was effected in the Summer of 1876—white seedling upon white, and the offspring is all white. I have now of them (Feb., 1879) about a thousand varieties, of most beautiful shapes, excellent qualities and immense yields, at least two hundred and fifty of them being disease-proof for so far, and the remainder being very slightly affected. The next cross—seedling upon seedling, as before, and not a cross in the second generation—was made in 1877, using a white father and red mother, and the offspring is part red, part white, and part mottled. Of these I have about three thousand varieties; about one thousand being disease-proof for so far—shapes, qualities, and yields being, as before, of great excellence.

Last season (1878), under Mr. Darwin’s wonderfully kind and minute instructions,9 I made many crosses of the second generation; have sown the seed, which is now growing vigorously, and I await a favourable result with great confidence.

Finally, Sir, should you consider this matter worthy of publication, and should any of your readers desire to communicate with me, I shall have great pleasure in responding.—

I am, Sir, | very respectfully yours, JAMES TORBITT.

Belfast, Feb., 1879

CD annotations

4.3 complete … obtained. 4.4] triple scored pencil
5.1 on] ‘on’ written above pencil
5.2 I … requisite, 5.3] triple scored pencil
5.4 expenditure] ‘d’ written over ‘d’ pencil
5.4 trade] ‘d’ written over ‘d’ pencil
7.1 In … observed. 7.2] scored pencil

Footnotes

CD’s letter of 20 September has not been found; see, however, the letter from James Torbitt, 18 September 1879.
CD had grown the ‘Black seventy-five’, a potato variety named by Torbitt; see CD’s note to the letter from James Torbitt, 1 May 1879. CD’s report to Torbitt has not been found.
The enclosure with Torbitt’s annotations has not been found; however, a reprint of Torbitt’s letter dated ‘Feb., 1879’ and published in the Field, 8 March 1879, p. 272, is in DAR 52: E3 and is transcribed as an enclosure.
For CD’s advice to Torbitt prior to the publication of Cross and self fertilisation, see Correspondence vol. 24, letter from James Torbitt, 14 April 1876, and letter to James Torbitt, 21 April 1876.
Torbitt presented a paper on potato disease at the British Association for the Advancement of Science meeting in Belfast in 1874 (see Report of the 44th meeting of the British Association for the Advancement of Science, held at Belfast (1874), Transactions of the sections, p. 134).
Peronospora infestans (now Phytophthora infestans) is a parasitic water mould responsible for causing potato late blight. The cycle of infection had been demonstrated by Anton de Bary in the 1860s (DSB).

Summary

Success of his experiments; report on recent work.

Letter details

Letter no.
DCP-LETT-12292
From
James Torbitt
To
Charles Robert Darwin
Sent from
Belfast
Source of text
DAR 52: E3; DAR 178: 155
Physical description
ALS 5pp †

Please cite as

Darwin Correspondence Project, “Letter no. 12292,” accessed on 29 March 2024, https://www.darwinproject.ac.uk/letter/?docId=letters/DCP-LETT-12292.xml

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