The Life and Letters-2 [221]
the least effect on the stigma of the other form. Taking sexual power as the criterion of difference, the two forms of this one species may be said to be generically distinct.")
[On the same subject he wrote to Sir Joseph Hooker in August 1862:--
"Is Oliver at Kew? When I am established at Bournemouth I am completely mad to examine any fresh flowers of any Lythraceous plant, and I would write and ask him if any are in bloom."
Again he wrote to the same friend in October:--
"If you ask Oliver, I think he will tell you I have got a real odd case in Lythrum, it interests me extremely, and seems to me the strangest case of propagation recorded amongst plants or animals, viz. a necessary triple alliance between three hermaphrodites. I feel sure I can now prove the truth of the case from a multitude of crosses made this summer."
In an article, 'Dimorphism in the Genitalia of Plants' ('Silliman's Journal,' 1862, volume xxxiv. page 419), Dr. Gray pointed out that the structural difference between the two forms of Primula had already been defined in the 'Flora of North America,' as DIOECIO-DIMORPHISM. The use of this term called forth the following remarks from my father. The letter also alludes to a review of the 'Fertilisation of Orchids' in the same volume of 'Silliman's Journal.']
CHARLES DARWIN TO ASA GRAY. Down, November 26 [1862].
My dear Gray,
The very day after my last letter, yours of November 10th, and the review in 'Silliman,' which I feared might have been lost, reached me. We were all very much interested by the political part of your letter; and in some odd way one never feels that information and opinions painted in a newspaper come from a living source; they seem dead, whereas all that you write is full of life. The reviews interested me profoundly; you rashly ask for my opinion, and you must consequently endure a long letter. First for Dimorphism; I do not AT PRESENT like the term "Dioecio-dimorphism;" for I think it gives quite a false notion, that the phenomena are connected with a separation of the sexes. Certainly in Primula there is unequal fertility in the two forms, and I suspect this is the case with Linum; and, therefore I felt bound in the Primula paper to state that it might be a step towards a dioecious condition; though I believe there are no dioecious forms in Primulaceae or Linaceae. But the three forms in Lythrum convince me that the phenomenon is in no way necessarily connected with any tendency to separation of sexes. The case seems to me in result or function to be almost identical with what old C.K. Sprengel called "dichogamy," and which is so frequent in truly hermaphrodite groups; namely, the pollen and stigma of each flower being mature at different periods. If I am right, it is very advisable not to use the term "dioecious," as this at once brings notions of separation of sexes.
...I was much perplexed by Oliver's remarks in the 'Natural History Review' on the Primula case, on the lower plants having sexes more often separated than in the higher plants,--so exactly the reverse of what takes place in animals. Hooker in his review of the 'Orchids' repeats this remark. There seems to be much truth in what you say ("Forms which are low in the scale as respects morphological completeness may be high in the scale of rank founded on specialisation of structure and function."--Dr. Gray, in 'Silliman's Journal.'), and it did not occur to me, about no improbability of specialisation in CERTAIN lines in lowly organised beings. I could hardly doubt that the hermaphrodite state is the aboriginal one. But how is it in the conjugation of Confervae--is not one of the two individuals here in fact male, and the other female? I have been much puzzled by this contrast in sexual arrangements between plants and animals. Can there be anything in the following consideration: By ROUGHEST calculation about one-third of the British GENERA of aquatic plants belong to the Linnean classes of Mono and Dioecia; whilst of terrestrial plants (the aquatic genera being subtracted)
[On the same subject he wrote to Sir Joseph Hooker in August 1862:--
"Is Oliver at Kew? When I am established at Bournemouth I am completely mad to examine any fresh flowers of any Lythraceous plant, and I would write and ask him if any are in bloom."
Again he wrote to the same friend in October:--
"If you ask Oliver, I think he will tell you I have got a real odd case in Lythrum, it interests me extremely, and seems to me the strangest case of propagation recorded amongst plants or animals, viz. a necessary triple alliance between three hermaphrodites. I feel sure I can now prove the truth of the case from a multitude of crosses made this summer."
In an article, 'Dimorphism in the Genitalia of Plants' ('Silliman's Journal,' 1862, volume xxxiv. page 419), Dr. Gray pointed out that the structural difference between the two forms of Primula had already been defined in the 'Flora of North America,' as DIOECIO-DIMORPHISM. The use of this term called forth the following remarks from my father. The letter also alludes to a review of the 'Fertilisation of Orchids' in the same volume of 'Silliman's Journal.']
CHARLES DARWIN TO ASA GRAY. Down, November 26 [1862].
My dear Gray,
The very day after my last letter, yours of November 10th, and the review in 'Silliman,' which I feared might have been lost, reached me. We were all very much interested by the political part of your letter; and in some odd way one never feels that information and opinions painted in a newspaper come from a living source; they seem dead, whereas all that you write is full of life. The reviews interested me profoundly; you rashly ask for my opinion, and you must consequently endure a long letter. First for Dimorphism; I do not AT PRESENT like the term "Dioecio-dimorphism;" for I think it gives quite a false notion, that the phenomena are connected with a separation of the sexes. Certainly in Primula there is unequal fertility in the two forms, and I suspect this is the case with Linum; and, therefore I felt bound in the Primula paper to state that it might be a step towards a dioecious condition; though I believe there are no dioecious forms in Primulaceae or Linaceae. But the three forms in Lythrum convince me that the phenomenon is in no way necessarily connected with any tendency to separation of sexes. The case seems to me in result or function to be almost identical with what old C.K. Sprengel called "dichogamy," and which is so frequent in truly hermaphrodite groups; namely, the pollen and stigma of each flower being mature at different periods. If I am right, it is very advisable not to use the term "dioecious," as this at once brings notions of separation of sexes.
...I was much perplexed by Oliver's remarks in the 'Natural History Review' on the Primula case, on the lower plants having sexes more often separated than in the higher plants,--so exactly the reverse of what takes place in animals. Hooker in his review of the 'Orchids' repeats this remark. There seems to be much truth in what you say ("Forms which are low in the scale as respects morphological completeness may be high in the scale of rank founded on specialisation of structure and function."--Dr. Gray, in 'Silliman's Journal.'), and it did not occur to me, about no improbability of specialisation in CERTAIN lines in lowly organised beings. I could hardly doubt that the hermaphrodite state is the aboriginal one. But how is it in the conjugation of Confervae--is not one of the two individuals here in fact male, and the other female? I have been much puzzled by this contrast in sexual arrangements between plants and animals. Can there be anything in the following consideration: By ROUGHEST calculation about one-third of the British GENERA of aquatic plants belong to the Linnean classes of Mono and Dioecia; whilst of terrestrial plants (the aquatic genera being subtracted)