There was still much work to be done, and in October he was still receiving Orchids from Kew, and wrote to Hooker:--
"It is impossible to thank you enough. I was almost mad at the wealth of Orchids." And again--
"Mr. Veitch most generously has sent me two splendid buds of Mormodes, which will be capital for dissection, but I fear will never be irritable; so for the sake of charity and love of heaven do, I beseech you, observe what movement takes place in Cychnoches, and what part must be touched. Mr. V. has also sent me one splendid flower of Catasetum, the most wonderful Orchid I have seen."
On October 13 he wrote to Sir Joseph Hooker:--
"It seems that I cannot exhaust your good nature. I have had the hardest day"s work at Catasetum and buds of Mormodes, and believe I understand at last the mechanism of movements and the functions. Catasetum is a beautiful case of slight modification of structure leading to new functions. I never was more interested in any subject in all my life than in this of Orchids. I owe very much to you."
Again to the same friend, November 1, 1861:--
"If you really can spare another Catasetum, when nearly ready, I shall be most grateful; had I not better send for it? The case is truly marvellous; the (so-called) sensation, or stimulus from a light touch is certainly transmitted through the antennae for more than one inch _instantaneously_.... A cursed insect or something let my last flower off last night."
Professor de Candolle has remarked[284] of my father, "Ce n"est pas lui qui aurait demande de construire des palais pour y loger des laboratoires." This was singularly true of his orchid work, or rather it would be nearer the truth to say that he had no laboratory, for it was only after the publication of the _Fertilisation of Orchids_, that he built himself a greenhouse. He wrote to Sir J. D. Hooker (December 24th, 1862):--
"And now I am going to tell you a _most_ important piece of news!! I have almost resolved to build a small hot-house; my neighbour"s really first-rate gardener has suggested it, and offered to make me plans, and see that it is well done, and he is really a clever follow, who wins lots of prizes, and is very observant. He believes that we should succeed with a little patience; it will be a grand amus.e.m.e.nt for me to experiment with plants."
Again he wrote (February 15th, 1863):--
"I write now because the new hot-house is ready, and I long to stock it, just like a schoolboy. Could you tell me pretty soon what plants you can give me; and then I shall know what to order? And do advise me how I had better get such plants as you can _spare_. Would it do to send my tax-cart early in the morning, on a day that was not frosty, lining the cart with mats, and arriving here before night? I have no idea whether this degree of exposure (and of course the cart would be cold) could injure stove-plants; they would be about five hours (with bait) on the journey home."
A week later he wrote:--
"You cannot imagine what pleasure your plants give me (far more than your dead Wedgwood-ware can give you); H. and I go and gloat over them, but we privately confessed to each other, that if they were not our own, perhaps we should not see such transcendant beauty in each leaf."
And in March, when he was extremely unwell, he wrote:--
"A few words about the stove-plants; they do so amuse me. I have crawled to see them two or three times. Will you correct and answer, and return enclosed. I have hunted in all my books and cannot find these names, and I like much to know the family." His difficulty with regard to the names of plants is ill.u.s.trated, with regard to a Lupine on which he was at work, in an extract from a letter (July 21, 1866) to Sir J. D. Hooker: "I sent to the nursery garden, whence I bought the seed, and could only hear that it was "the common blue Lupine," the man saying "he was no scholard, and did not know Latin, and that parties who make experiments ought to find out the names.""
The book was published May 15th, 1862. Of its reception he writes to Mr.
Murray, June 13th and 18th:--
"The Botanists praise my Orchid-book to the skies. Some one sent me (perhaps you) the _Parthenon_, with a good review. The _Athenaeum_[285]
treats me with very kind pity and contempt; but the reviewer knew nothing of his subject."
"There is a superb, but I fear exaggerated, review in the _London Review_.[286] But I have not been a fool, as I thought I was, to publish; for Asa Gray, about the most competent judge in the world, thinks almost as highly of the book as does the _London Review_. The _Athenaeum_ will hinder the sale greatly."
The Rev. M. J. Berkeley was the author of the notice in the _London Review_, as my father learned from Sir J. D. Hooker, who added, "I thought it very well done indeed. I have read a good deal of the Orchid-book, and echo all he says."
To this my father replied (June 30th, 1862):--
"My dear old friend,--You speak of my warming the c.o.c.kles of your heart, but you will never know how often you have warmed mine. It is not your approbation of my scientific work (though I care for that more than for any one"s): it is something deeper. To this day I remember keenly a letter you wrote to me from Oxford, when I was at the Water-cure, and how it cheered me when I was utterly weary of life. Well, my Orchid-book is a success (but I do not know whether it sells)."
In another letter to the same friend, he wrote:--
"You have pleased me much by what you say in regard to Bentham and Oliver approving of my book; for I had got a sort of nervousness, and doubted whether I had not made an egregious fool of myself, and concocted pleasant little stinging remarks for reviews, such as "Mr.
Darwin"s head seems to have been turned by a certain degree of success, and he thinks that the most trifling observations are worth publication.""
He wrote too, to Asa Gray:--
"Your generous sympathy makes you over-estimate what you have read of my Orchid-book. But your letter of May 18th and 26th has given me an almost foolish amount of satisfaction. The subject interested me, I knew, beyond its real value; but I had lately got to think that I had made myself a complete fool by publishing in a semi-popular form. Now I shall confidently defy the world.... No doubt my volume contains much error: how curiously difficult it is to be accurate, though I try my utmost.
Your notes have interested me beyond measure. I can now afford to d---- my critics with ineffable complacency of mind. Cordial thanks for this benefit."
Sir Joseph Hooker reviewed the book in the _Gardeners" Chronicle_, writing in a successful imitation of the style of Lindley, the Editor.
My father wrote to Sir Joseph (Nov. 12, 1862):--
"So you did write the review in the _Gardeners" Chronicle_. Once or twice I doubted whether it was Lindley; but when I came to a little slap at R. Brown, I doubted no longer. You arch-rogue! I do not wonder you have deceived others also. Perhaps I am a conceited dog; but if so, you have much to answer for; I never received so much praise, and coming from you I value it much more than from any other."
With regard to botanical opinion generally, he wrote to Dr. Gray, "I am fairly astonished at the success of my book with botanists." Among naturalists who were not botanists, Lyell was pre-eminent in his appreciation of the book. I have no means of knowing when he read it, but in later life, as I learn from Professor Judd, he was enthusiastic in praise of the _Fertilisation of Orchids_, which he considered "next to the _Origin_, as the most valuable of all Darwin"s works." Among the general public the author did not at first hear of many disciples, thus he wrote to his cousin Fox in September 1862: "Hardly any one not a botanist, except yourself, as far as I know, has cared for it."
If we examine the literature relating to the fertilisation of flowers, we do not find that this new branch of study showed any great activity immediately after the publication of the Orchid-book. There are a few papers by Asa Gray, in 1862 and 1863, by Hildebrand in 1864, and by Moggridge in 1865, but the great ma.s.s of work by Axell, Delpino, Hildebrand, and the Mullers, did not begin to appear until about 1867.
The period during which the new views were being a.s.similated, and before they became thoroughly fruitful, was, however, surprisingly short. The later activity in this department may be roughly gauged by the fact that the valuable "Bibliography," given by Professor D"Arcy Thompson in his translation of Muller"s _Befruchtung_ (1883),[287] contains references to 814 papers.
In 1877 a second edition of the _Fertilisation of Orchids_ was published, the first edition having been for some time out of print. The new edition was remodelled and almost rewritten, and a large amount of new matter added, much of which the author owed to his friend Fritz Muller.
With regard to this edition he wrote to Dr. Gray:--
"I do not suppose I shall ever again touch the book. After much doubt I have resolved to act in this way with all my books for the future; that is to correct them once and never touch them again, so as to use the small quant.i.ty of work left in me for new matter."
One of the latest references to his Orchid-work occurs in a letter to Mr. Bentham, February 16, 1880. It shows the amount of pleasure which this subject gave to my father, and (what is characteristic of him) that his reminiscence of the work was one of delight in the observations which preceded its publication, not to the applause which followed it:--
"They are wonderful creatures, these Orchids, and I sometimes think with a glow of pleasure, when I remember making out some little point in their method of fertilisation."
_The Effect of Cross-and Self-fertilisation in the Vegetable Kingdom.
Different Forms of Flowers on Plants of the same species._
Two other books bearing on the problem of s.e.x in plants require a brief notice. _The Effects of Cross- and Self-Fertilisation_, published in 1876, is one of his most important works, and at the same time one of the most unreadable to any but the professed naturalist. Its value lies in the proof it offers of the increased vigour given to the offspring by the act of cross-fertilisation. It is the complement of the Orchid book because it makes us understand the advantage gained by the mechanisms for insuring cross-fertilisation described in that work.
The book is also valuable in another respect, because it throws light on the difficult problems of the origin of s.e.xuality. The increased vigour resulting from cross-fertilisation is allied in the closest manner to the advantage gained by change of conditions. So strongly is this the case, that in some instances cross-fertilisation gives no advantage to the offspring, unless the parents have lived under slightly different conditions. So that the really important thing is not that two individuals of different _blood_ shall unite, but two individuals which have been subjected to different conditions. We are thus led to believe that s.e.xuality is a means for infusing vigour into the offspring by the coalescence of differentiated elements, an advantage which could not accompany as.e.xual reproductions.
It is remarkable that this book, the result of eleven years of experimental work, owed its origin to a chance observation. My father had raised two beds of _Linaria vulgaris_--one set being the offspring of cross and the other of self-fertilisation. The plants were grown for the sake of some observations on inheritance, and not with any view to cross-breeding, and he was astonished to observe that the offspring of self-fertilisation were clearly less vigorous than the others. It seemed incredible to him that this result could be due to a single act of self-fertilisation, and it was only in the following year, when precisely the same result occurred in the case of a similar experiment on inheritance in carnations, that his attention was "thoroughly aroused," and that he determined to make a series of experiments specially directed to the question.
The volume on _Forms of Flowers_ was published in 1877, and was dedicated by the author to Professor Asa Gray, "as a small tribute of respect and affection." It consists of certain earlier papers re-edited, with the addition of a quant.i.ty of new matter. The subjects treated in the book are:--
(i.) Heterostyled Plants.
(ii.) Polygamous, Dioecious, and Gynodioecious Plants.
(iii.) Cleistogamic Flowers.
The nature of heterostyled plants may be ill.u.s.trated in the primrose, one of the best known examples of the cla.s.s. If a number of primroses be gathered, it will be found that some plants yield nothing but "pin-eyed"
flowers, in which the style (or organ for the transmission of the pollen to the ovule) is long, while the others yield only "thrum-eyed" flowers with short styles. Thus primroses are divided into two sets or castes differing structurally from each other. My father showed that they also differ s.e.xually, and that in fact the bond between the two castes more nearly resembles that between separate s.e.xes than any other known relationship. Thus for example a long-styled primrose, though it can be fertilised by its own pollen, is not _fully_ fertile unless it is impregnated by the pollen of a short-styled flower. Heterostyled plants are comparable to hermaphrodite animals, such as snails, which require the concourse of two individuals, although each possesses both the s.e.xual elements. The difference is that in the case of the primrose it is _perfect fertility_, and not simply _fertility_, that depends on the mutual action of the two sets of individuals.
The work on heterostyled plants has a special bearing, to which the author attached much importance, on the problem of the origin of species.[288]