244 Influence of Environment on Plants 



still retain 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 bj 

 Blaringhem 1 . 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. Tri/olium 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 2 who injected 

 strong (10%) 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 ele- 

 mentary 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 ob- 

 tained 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, how- 

 ever, 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 



1 Blaringhem, Mutation et Traumatisme, Paris, 1907. 



2 MacDougal, " Heredity and Origin of species," Monist, 1906; " Keport of department nf 

 botanical research," Fifth Year-book of the Carnegie Institution of Washington, p. 119, 1907. 



