OBSERVABLE PROPERTIES OF EACH SPECIES 21 



and this property is variable. * Nothing, however, is changed 

 in the speciiic plasticity. The property fasciation becomes 

 visible, in the same way in which the floating leaves of Ranun- 

 culus sceleratus (see § 12) become visible when this species is 

 developed in water. 



§ 26.— VARIATION UNDER CULTIVATION [continued). 

 COMPLEX SPECIES. — Suppose now that the species which is 

 brought under cultivation is a complex one, consisting, for in- 

 stance, of two subspecies. If these coexist in the same locahty 

 (which is very often the case) , hybrids may occur. Many hybrid 

 specimens resemble one of the parents, although one (or several) 

 properties of the other parent are latent in them. If one of the 

 seeds collected in the state of nature is a hybrid, we may obtain 

 in the garden, in the first or in the second cultivated generation, 

 specimens of two kinds (regression, MENDEL), and according 

 to the principle of segregation (MENDEL. See § 33), it may 

 happen that even more than two kinds of plants appear, 

 and this may be repeated in several successive cultivated 

 generations.^ 



Numerous species which are looked upon as being mono- 

 typic are actually complex. Some of their subspecies, being 

 rather rare, are overlooked or looked upon as being occasional 

 deviations, monstrosities, anomalies and, in general, curios- 

 ities.^ On the other hand, many of them have been described 

 as varieties or species properly so called.* It may therefore be 

 surmised that many species which have afforded examples of 

 new properties when brought rnider cultivation were actually 

 complex species. If we don't know that a cultivated species 

 is complex, we may be tempted to beUeve that variation has 



1 In the given example (observed in my private garden with (Enothera 

 biennis ; seeds collected at Deurel, near Ghent) the difierences between the 

 cultivated specimens with regard to fasciation depend on differences in the 

 conditions of existence. These conditions are always different from one 

 specimen to another, even when all possible precautions to avoid them are 

 taken by the gardener. If the plants, for instance, are sown in a seed-pan and 

 afterwards transplanted one by one, a slight difference in the manipulation 

 of two specimens (roots more or less disturbed, young stems more or less 

 pressed between the fingers, etc.) may have an important influence upon their 

 further development. 



' In this way new forms (new combinations of properties), which have never 

 been observed before, may be obtained. 



' EXAMPLE : In Flanders, Centaurea cyanus includes, as far as I know, three 

 subspecies : (i) blue flowers, very common ; (2) white flowers, uncommon ; 

 (3) purplish flowers, rare. Many seed-fixed subspecies of Centaurea cyanus 

 are found in seedsmen's catalogues (see, for instance, the price list of HAAGE 

 and SCHMIDT, Erfurt). See also Solanum nigrum, § 13. 



* Innumerable species of Mentha, Salicorma, Erythrtsa and many other 

 polymorphic genera have been described. Although the great majority of these 

 so-called species are simply based upon variants (variations produced by con- 

 ditions of existence), there are certainly a number of subspecies among them. 



