RECORD: Darwin, C. R. 1879. [Letter to Wilson, 1878]. In A. Stephen Wilson, Experiments with Kubanka and Saxonica wheat. First year's experiments and results. Gardeners' Chronicle, 11, no. 282 (24 May): 652-4, p. 652.

REVISION HISTORY: Transcribed and edited by John van Wyhe 5.2022. RN2

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Darwin's letter to the Scottish civil engineer and botanist Alexander Stephen Wilson,(1827-1893) was printed (based on his original draft) in ML 2: 420 with the following commentary:

"The following letters refer to two forms of wheat cultivated in Russia under the names Kubanka and Saxonka, which had been sent to Mr. Darwin by Dr. Asher from Samara, and were placed in the hands of Mr. Wilson that he might test the belief prevalent in Russia that Kubanka "grown repeatedly on inferior soil," assumes "the form of  Saxonka." Mr. Wilson's paper of 1880 gives the results of his inquiry. He concludes (basing his views partly on analogous cases and partly on his study of the Russian wheats) that the supposed transformation is explicable in chief part by the greater fertility of the Saxonka wheat leading to extermination of the other form. According to Mr. Wilson, therefore, the Saxonka survivors are incorrectly assumed to be the result of the conversion of one form into the other."

The text of the letter published in Correspondence vol. 26, p. 168, includes as the second sentence "Any how they are of no use to me as I have neither knowledge or time sufficient." which is absent from the text published here. The Correspondence text was taken from Darwin's original draft copy in CUL-DAR148.364. Wilson published his final results in Gardeners' Chronicle, (7 February 1880): 172-3.

[page] 652



IN April, 1878, I had the honour of receiving the following letter:—

"Down, Beckenham, Kent, April 24.

"My dear Sir,—I send you herewith some specimens which may perhaps interest you, as you have so carefully studied the varieties of Wheat. They were sent me by the governor of the province of Samara in Russia, at the request of Dr. Asher (son of the great Berlin publisher), who farmed for some years in the province. The specimens marked Kubankais a very valuable kind, but which keeps true only when cultivated in fresh steppe-land in Samara, and in Saratoff.  After two years it degenerates into the variety Saxonicaor its synonym Ghirca. The latter alone is imported into this country. Dr. Asher says that it is universally known, and he has himself witnessed the fact, that if grain of the Kubanka be sown in the same steppe-land for more than two years it changes into Saxonica. He has seen a field with parts still Kubanka and the remainder Saxonica. On this account the Government in letting steppe-land, contract that after two years Wheat must not be sown again until an interval of eight years.

"The ears of the two kinds appear different as you will see, but the chief difference is in the quality of the grains. Dr. Asher has witnessed sales of equal weights of Kubanka and Saxonica grain, and the price of the former was to that of the latter as 7 : 4. The peasants say that the change commences in the terminal grain of the ear. The most remarkable point as Dr. Asher positively asserts, is that there are no intermediate varieties; but that a grain produces a plant yielding either true Kubanka or true Saxonica. He thinks that it would be interesting to sow here both kinds, in a good and bad Wheat soil and observe the result. Should you think it worth while to make any such trials, and should you require further information, Dr. Asher, whose address I enclose, will be happy to give any in his power. I hope that I have not troubled you uselessly and remain,

"My dear Sir, yours faithfully,

(Signed) "CH. DARWIN."

"Mr. A. Stephen Wilson."

On receiving the two Wheats described in Mr. Darwin's letter, I immediately set to work. I was occupied at the time repeating M. Fabre's experiments with Ægilops, and it was possible the one set of experiments would throw some light upon the other. But before detailing my first year's operations, I would beg to give such description of Kubanka and Saxonica Wheat as may help to show in what particulars the one differs from the other.

Kubanka belongs to the class of Wheats called turgid. The ear is compact or thickset, there being on each side of the rachis four spikelets in the length of an inch, and eight or nine ranks of spikelets in the ear. The glumes are very smooth and reflect the light. The awns are about twice the length of the rachis. In the ears sent to me none of the spikelets had more than two grains or fertile florets. The straw, for some distance below the ear, is nearly solid. The grains are about .24 of an inch in length, and of a faint yellow colour, the average weighing about .56 of a troy grain, and the best seeds .66, and a good ear containing about thirty-six seeds. (Fig. 93— figs. 1 and 3).

Saxonica is not distinguishable from ordinary awny spring Wheat. It has an open or thin-set ear, there being three spikelets on a side in about the length of 1 inch, and seven or eight ranks in the ear. The awns are about the same length as the rachis. In some of the ears the chaff-scales (glumes and pales) are reddish, and in others white. The straw or culm is a hollow tube throughout. The grain is what is called a red Wheat, and is about .25 of an inch in length, weighs on an average .45 of a troy grain, the best seeds weighing .52, and the best ears containing from thirty to forty seeds. (Fig. 93—figs. 2 and 4).

The Kubanka figures on the left hand of the illustration (1, 3, 5, 7, 9,) may be compared with the Saxonica figures on the right (2, 4, 6, 8, 10). Figs. 1 and 2 are the edge views of ears as traced directly on thin horn plates, the awns being shortened for want of room. Fig. 3 is a front view of a Kubanka spikelet of two grains; fig. 4 the same view of a Saxonica spikelet of three grains, though many of the spikelets have only two; fig. 5 is a transverse section of a grain of Kubanka near the middle, to show the form of the grain; fig. 6 is the corresponding section of a grain of Saxonica; fig. 7 is a transverse section of the coats of a Kubanka grain as expanded in water and magnified 184 times; fig. 8 is the corresponding section of Saxonica, a, a, is the epicarp, which is thicker in the Kubanka than in the Saxonica in the proportion of 100 to 74; b, b, is a delicate membrane underlying the epicarp; c, c, is the proper exterior of the fruit, in which is developed the colouring matter which makes one Wheat a "white" Wheat, another a "yellow," and another a "red." The Kubanka is a yellowish Wheat, the Saxonica a reddish. Under the testa lies a matrix of clear gum, extending from c to f and running up the veins through the starch granules towards the midrib. In the matrix, c, f , the cells, e, e, lie over the whole exterior of the grain. Seen from above, or in plan, they are nearly hexagonal in form, as if an irregular honeycomb were deposited on the surface, with canals of transparent gum between the cells. The aleurone grains filling these cells are small, and give the albuminoid reaction with iodine.

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The aspect of evolution thus presented is not that of transformation, but that of the extinction of the less prolific by the more prolific, of the weaker by the stronger. It is just because the one form of Wheat cannot readily change into the other that a struggle for predominance is possible. Without any change of form in a given flora an entire change of scene thus creeps over vegetation, presenting new kinds of animal food and giving physiological impulses new directions. Nor can there be any doubt that changes of form are much more slowly worked out than changes of flora. But with the altered vegetable soil, for example, arising from an incursion of dominant forms, new cosmical factors come into operation, and change of form may at length be the necessary resultant. Both processes are the harmonious details, the insensible steps of that great daily work going on before our eyes, which embraces  the moulding of a plant and the making of a planet.

A. Stephen Wilson.

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