From Robert Caspary 2 April 1868
Koenigsberg in Pr.
2nd of April 1868
My dear Sir
Many thanks for your letter of the 25th of Febr.1 I received now a few days ago an english copy of your “variation of animals and plants” and even the first edition, which I conclude from this, that the passages concerning grafhybrids are just the same as in the german translation.2 Now I shall begin to read your work in English with greatest interest.
I long to hear, what case it could be, that Hildebrand has found as regards grafthybrids, which is quite conclusive.
I regret very much, that I am unable to fullfill your wish as regards the seed of Euryale, got by crossed and self fertilized flowers, as I did not keep them separated.3 I separated the seeds as regards an other point of view i.e. whether the flower had remained closed under water or had risen above water and opened. So 1866—
In 1867 I was absent for 7 weeks going to Alsatia and the black forest for studying the Nuphars there and I could not attend to Euryale.4 I wanted to find out as an object of interest, whether the seeds of the submerged flowers or of the open ones germinated better—
Up to this time I can not yet give a precise answer as regarding the seeds of 1866, but the close of the experiment is approaching. Euryale is a very extraordinary plant as regards the condition of its stigma, indeed so much, that I know of no parallel. The stigma is perfectly dry, secreting no fluid at all. The pollen is lying upon it perfectly as dry dust and shed over it quite equally— Therefore I can fancy, that, if by application of a brush, by which the pollen of an other flower is put upon the stigma, the own pollen is partely removed and its equally spreading disturbed, fertilisation may finally in someway be checked. But the few cases in which I crossed the flowers of Euryale, are still too few in number, and I will try to get more. I suppose, that when the flower finally sinks under water, or keeps under water in the latter part of its flowering, the fluid of the water itself may moisten the dry pollen. As regards Nymphaeaceae it would be most difficult to try the growth of crossed seeds compared with self fertilised seed on account of the plants wanting so much space. I grow always 2 plants of Euryale, but each requires 16 feet square i.e. 256 square feet space, but my plants are of a size, which superseeds any thing I saw before.— And the culture of Nymphaeaceae requires a great deal of care, so much so, that, although I have most conscientious assistants, I do as much as I can always myself or give instant orders even for the most minute things— At Kew I think they do not care much for Nymphaeaceae— They never had many species and one most valuable Nymphaea (elegans Hook.)5 which they reared at Kew from Mine own seeds, they soon lost to my very great regret.— That your health is better, I am most glad to hear; may it make further good progress.—
My best regards to Mrs. Darwin— I am glad our King sent you the order pour le merit. But how foolish that it has a french name! For this the time of Frederic II accounts.6
Believe me | my dear Sir, yours most truly | Rob. Caspary
Finds important differences between English and German versions of Variation on graft-hybrids.
Experiments and observations on submerged flowers.
Please cite as
Darwin Correspondence Project, “Letter no. 6083,” accessed on 27 May 2016, http://www.darwinproject.ac.uk/DCP-LETT-6083