Darwin and Modern Science [278]
from the data other conclusions than those of the author. Each investigation is the outcome of a definite question, a "preconceived opinion," which is either supported by the facts or must be abandoned. "How odd it is that anyone should not see that all observation must be for or against some view if it is to be of any service!" (Ibid. Vol. I. page 195.)
The points of view which Darwin had before him were principally the following. In the first place the proof that a large number of the peculiarities in the structure of flowers are not useless, but of the greatest significance in pollination must be of considerable importance for the interpretation of adaptations; "The use of each trifling detail of structure is far from a barren search to those who believe in natural selection." ("Fertilisation of Orchids" (1st edition), page 351; (2nd edition 1904) page 286.) Further, if these structural relations are shown to be useful, they may have been acquired because from the many variations which have occurred along different lines, those have been preserved by natural selection "which are beneficial to the organism under the complex and ever-varying conditions of life." (Ibid. page 351.) But in the case of flowers there is not only the question of adaptation to fertilisation to be considered. Darwin, indeed, soon formed the opinion which he has expressed in the following sentence,--"From my own observations on plants, guided to a certain extent by the experience of the breeders of animals, I became convinced many years ago that it is a general law of nature that flowers are adapted to be crossed, at least occasionally, by pollen from a distinct plant." ("Cross and Self fertilisation" (1st edition), page 6.)
The experience of animal breeders pointed to the conclusion that continual in-breeding is injurious. If this is correct, it raises the question whether the same conclusion holds for plants. As most flowers are hermaphrodite, plants afford much more favourable material than animals for an experimental solution of the question, what results follow from the union of nearly related sexual cells as compared with those obtained by the introduction of new blood. The answer to this question must, moreover, possess the greatest significance for the correct understanding of sexual reproduction in general.
We see, therefore, that the problems which Darwin had before him in his researches into the biology of flowers were of the greatest importance, and at the same time that the point of view from which he attacked the problems was essentially a teleological one.
We may next inquire in what condition he found the biology of flowers at the time of his first researches, which were undertaken about the year 1838. In his autobiography he writes,--"During the summer of 1839, and, I believe, during the previous summer, I was led to attend to the cross- fertilisation of flowers by the aid of insects, from having come to the conclusion in my speculations on the origin of species, that crossing played an important part in keeping specific forms constant." ("The Life and Letters of Charles Darwin", Vol. I. page 90, London, 1888.) In 1841 he became acquainted with Sprengel's work: his researches into the biology of flowers were thus continued for about forty years.
It is obvious that there could only be a biology of flowers after it had been demonstrated that the formation of seeds and fruit in the flower is dependent on pollination and subsequent fertilisation. This proof was supplied at the end of the seventeenth century by R.J. Camerarius (1665- 1721). He showed that normally seeds and fruits are developed only when the pollen reaches the stigma. The manner in which this happens was first thoroughly investigated by J.G. Kolreuter (1733-1806 (Kolreuter, "Vorlaufige Nachricht von einigen das Geschlecht der Planzen betreffenden Versuchen und Beobachtungen", Leipzig, 1761; with three supplements, 1763- 66. Also, "Mem. de l'acad. St Petersbourg", Vol. XV. 1809.)), the same observer to whom we owe the earliest experiments
The points of view which Darwin had before him were principally the following. In the first place the proof that a large number of the peculiarities in the structure of flowers are not useless, but of the greatest significance in pollination must be of considerable importance for the interpretation of adaptations; "The use of each trifling detail of structure is far from a barren search to those who believe in natural selection." ("Fertilisation of Orchids" (1st edition), page 351; (2nd edition 1904) page 286.) Further, if these structural relations are shown to be useful, they may have been acquired because from the many variations which have occurred along different lines, those have been preserved by natural selection "which are beneficial to the organism under the complex and ever-varying conditions of life." (Ibid. page 351.) But in the case of flowers there is not only the question of adaptation to fertilisation to be considered. Darwin, indeed, soon formed the opinion which he has expressed in the following sentence,--"From my own observations on plants, guided to a certain extent by the experience of the breeders of animals, I became convinced many years ago that it is a general law of nature that flowers are adapted to be crossed, at least occasionally, by pollen from a distinct plant." ("Cross and Self fertilisation" (1st edition), page 6.)
The experience of animal breeders pointed to the conclusion that continual in-breeding is injurious. If this is correct, it raises the question whether the same conclusion holds for plants. As most flowers are hermaphrodite, plants afford much more favourable material than animals for an experimental solution of the question, what results follow from the union of nearly related sexual cells as compared with those obtained by the introduction of new blood. The answer to this question must, moreover, possess the greatest significance for the correct understanding of sexual reproduction in general.
We see, therefore, that the problems which Darwin had before him in his researches into the biology of flowers were of the greatest importance, and at the same time that the point of view from which he attacked the problems was essentially a teleological one.
We may next inquire in what condition he found the biology of flowers at the time of his first researches, which were undertaken about the year 1838. In his autobiography he writes,--"During the summer of 1839, and, I believe, during the previous summer, I was led to attend to the cross- fertilisation of flowers by the aid of insects, from having come to the conclusion in my speculations on the origin of species, that crossing played an important part in keeping specific forms constant." ("The Life and Letters of Charles Darwin", Vol. I. page 90, London, 1888.) In 1841 he became acquainted with Sprengel's work: his researches into the biology of flowers were thus continued for about forty years.
It is obvious that there could only be a biology of flowers after it had been demonstrated that the formation of seeds and fruit in the flower is dependent on pollination and subsequent fertilisation. This proof was supplied at the end of the seventeenth century by R.J. Camerarius (1665- 1721). He showed that normally seeds and fruits are developed only when the pollen reaches the stigma. The manner in which this happens was first thoroughly investigated by J.G. Kolreuter (1733-1806 (Kolreuter, "Vorlaufige Nachricht von einigen das Geschlecht der Planzen betreffenden Versuchen und Beobachtungen", Leipzig, 1761; with three supplements, 1763- 66. Also, "Mem. de l'acad. St Petersbourg", Vol. XV. 1809.)), the same observer to whom we owe the earliest experiments