Darwin and Modern Science [171]
it, after vegetative propagation, in varying degrees. The same character occurs also in some of the seedlings; but anything approaching a constant race has not been produced.
Another means of producing new races has been attempted by Blaringhem. (Blaringhem, "Mutation et Traumatisme", Paris, 1907.) On removing at an early stage the main shoots of different plants he observed various abnormalities in the newly formed basal shoots. From the seeds of such plants he obtained races, a large percentage of which exhibited these abnormalities. Starting from a male Maize plant with a fasciated inflorescence, on which a proportion of the flowers had become male, a new race was bred in which hermaphrodite flowers were frequently produced. In the same way Blaringhem obtained, among other similar results, a race of barley with branched ears. These races, however, behaved in essentials like those which have been demonstrated by de Vries to be inconstant, e.g. Trifolium pratense quinquefolium and others. The abnormality appears in a proportion of the individuals and only under very special conditions. It must be remembered too that Blaringhem worked with old cultivated plants, which from the first had been disposed to split into a great variety of races. It is possible, but difficult to prove, that injury contributed to this result.
A third method has been adopted by MacDougal (MacDougal, "Heredity and Origin of species", "Monist", 1906; "Report of department of botanical research", "Fifth Year-book of the Carnegie Institution of Washington", page 119, 1907.) who injected strong (10 percent) sugar solution or weak solutions of calcium nitrate and zinc sulphate into young carpels of different plants. From the seeds of a plant of Raimannia odorata the carpels of which had been thus treated he obtained several plants distinguished from the parent-forms by the absence of hairs and by distinct forms of leaves. Further examination showed that he had here to do with a new elementary species. MacDougal also obtained a more or less distinct mutant of Oenothera biennis. We cannot as yet form an opinion as to how far the effect is due to the wound or to the injection of fluid as such, or to its chemical properties. This, however, is not so essential as to decide whether the mutant stands in any relation to the influence of external factors. It is at any rate very important that this kind of investigation should be carried further.
If it could be shown that new and inherited races were obtained by MacDougal's method, it would be safe to conclude that the same end might be gained by altering the conditions of the food-stuff conducted to the sexual cells. New races or elementary species, however, arise without wounding or injection. This at once raises the much discussed question, how far garden-cultivation has led to the creation of new races? Contrary to the opinion expressed by Darwin and others, de Vries ("Mutationstheorie", Vol. I. pages 412 et seq.) tried to show that garden-races have been produced only from spontaneous types which occur in a wild state or from sub-races, which the breeder has accidentally discovered but not originated. In a small number of cases only has de Vries adduced definite proof. On the other side we have the work of Korschinsky (Korschinsky, "Heterogenesis und Evolution", "Flora", 1901.) which shows that whole series of garden-races have made their appearance only after years of cultivation. In the majority of races we are entirely ignorant of their origin.
It is, however, a fact that if a plant is removed from natural conditions into cultivation, a well-marked variation occurs. The well-known plant- breeder L. de Vilmorin (L. de Vilmorin, "Notices sur l'amelioration des plantes", Paris, 1886, page 36.), speaking from his own experience, states that a plant is induced to "affoler," that is to exhibit all possible variations from which the breeder may make a further selection only after cultivation for several generations. The effect of cultivation was particularly striking in Veronica
Another means of producing new races has been attempted by Blaringhem. (Blaringhem, "Mutation et Traumatisme", Paris, 1907.) On removing at an early stage the main shoots of different plants he observed various abnormalities in the newly formed basal shoots. From the seeds of such plants he obtained races, a large percentage of which exhibited these abnormalities. Starting from a male Maize plant with a fasciated inflorescence, on which a proportion of the flowers had become male, a new race was bred in which hermaphrodite flowers were frequently produced. In the same way Blaringhem obtained, among other similar results, a race of barley with branched ears. These races, however, behaved in essentials like those which have been demonstrated by de Vries to be inconstant, e.g. Trifolium pratense quinquefolium and others. The abnormality appears in a proportion of the individuals and only under very special conditions. It must be remembered too that Blaringhem worked with old cultivated plants, which from the first had been disposed to split into a great variety of races. It is possible, but difficult to prove, that injury contributed to this result.
A third method has been adopted by MacDougal (MacDougal, "Heredity and Origin of species", "Monist", 1906; "Report of department of botanical research", "Fifth Year-book of the Carnegie Institution of Washington", page 119, 1907.) who injected strong (10 percent) sugar solution or weak solutions of calcium nitrate and zinc sulphate into young carpels of different plants. From the seeds of a plant of Raimannia odorata the carpels of which had been thus treated he obtained several plants distinguished from the parent-forms by the absence of hairs and by distinct forms of leaves. Further examination showed that he had here to do with a new elementary species. MacDougal also obtained a more or less distinct mutant of Oenothera biennis. We cannot as yet form an opinion as to how far the effect is due to the wound or to the injection of fluid as such, or to its chemical properties. This, however, is not so essential as to decide whether the mutant stands in any relation to the influence of external factors. It is at any rate very important that this kind of investigation should be carried further.
If it could be shown that new and inherited races were obtained by MacDougal's method, it would be safe to conclude that the same end might be gained by altering the conditions of the food-stuff conducted to the sexual cells. New races or elementary species, however, arise without wounding or injection. This at once raises the much discussed question, how far garden-cultivation has led to the creation of new races? Contrary to the opinion expressed by Darwin and others, de Vries ("Mutationstheorie", Vol. I. pages 412 et seq.) tried to show that garden-races have been produced only from spontaneous types which occur in a wild state or from sub-races, which the breeder has accidentally discovered but not originated. In a small number of cases only has de Vries adduced definite proof. On the other side we have the work of Korschinsky (Korschinsky, "Heterogenesis und Evolution", "Flora", 1901.) which shows that whole series of garden-races have made their appearance only after years of cultivation. In the majority of races we are entirely ignorant of their origin.
It is, however, a fact that if a plant is removed from natural conditions into cultivation, a well-marked variation occurs. The well-known plant- breeder L. de Vilmorin (L. de Vilmorin, "Notices sur l'amelioration des plantes", Paris, 1886, page 36.), speaking from his own experience, states that a plant is induced to "affoler," that is to exhibit all possible variations from which the breeder may make a further selection only after cultivation for several generations. The effect of cultivation was particularly striking in Veronica