Half Races and Half Curves. 31 



side of the corolla in a half race of Linaria vulgaris 

 which I have stiulied for a few generations, and for 

 which the half curves have recently been plotted and in- 

 vestigated by Gar JEANNE.^ 



It is well known that every species has a tendency, 

 as the expression is, to vary in certain definite directions ; 

 in these the deviations occur fairly frequently, in others 

 either not at all or very seldom. The number of anom- 

 alies is by no means an unlimited one for a given species, 

 but strictly limited. One expression of this phenomenon 

 is the fact that one species tends to produce and repeat 

 one particular abnormality, and another species, another. 

 This general fact, with which we are familiar in vague 

 expressions of this kind, can be made the starting point 

 of valuable experimental investigations. For what are 

 we to understand by "tendency" in these cases? In my 

 opinion simply the existence of a half race or sometimes 

 even of an eversporting variety. These two types of 

 races are, so far as my experience reaches, perfectly dis- 

 tinct, and in numerous cases amenable to experimental 

 study ; they are things with nothing intrinsically vague 

 about them although they are sometimes blurred in their 

 manifestation, under a superficial examination, on ac- 

 count of the high degree of fluctuating variability which 

 they exhibit. 



If we take a plant which presents this tendency to a 

 particular anomaly and cultivate its progeny, isolating it 

 with an eye to this tendency, we shall usually find that we 

 are dealing with an intermediate race of the kind of which 

 w^e have spoken. I shall refer to an instance in the fol- 

 lowing section (§ 5) : but this will be only one out of 



'A. J. M. Garjeanne, Bcohachhmgcn nnd CiiUurvcrsuchc iiber 

 cine BliitJicnanomalic von Linaria vulgaris. Flora, 1901. Vol. 88, p. 

 78; with Plates IX and X. 



