HEREDITY BATESON. 3Y5 



positive characteristic and invert the expressions, representing the 

 red as RR^ the partly red as Rr, and the yellow as rr. Accord- 

 ing as we adopt the one or the other system of expression we shall 

 interpret the evolutionary change as one of loss or as one of addition. 

 May we not interpret the other apparent new dominants in the 

 same way? The white dominant in the fowl or in the Chinese 

 primula can inhibit color. But may it not be that the original 

 colored fowl or primula had tvro doses of a factor which inhibited 

 this inhibitor? The pepper moth, Amphidasys hetularia^ produced 

 in England about ISttO a black variety, then a novelty, now common 

 in certain areas, which behaves as a full dominant. The pure blacks 

 are no blacker than the crossbred. Though at first sight it seems that 

 the black must have been something added, we can without absurdity 

 suggest that the normal -is the term in which two doses of inhibitor 

 are present, and that in the absence of one of them the black appears. 



In spite of seeming perversity, therefore, we have to admit that 

 there is no evolutionary change which in the present state of our 

 knowledge we can positively declare to be not due to loss. When this 

 has been conceded it is natural to ask whether the removal of inhibit- 

 ing factors may not be invoked in alleviation of the necessity which 

 has driven students of the domestic breeds to refer their diversities 

 to multiple origins. Something, no doubt, is to be hoped for in that 

 direction, but not until much better and more extensive knowledge 

 of what variation by loss may effect in the living body can we have 

 any real assurance that this difficult}^ has lieen obviated. We should 

 be greatly helped by some indication as to whether the origin of 

 life has been single or multiple. IModern opinion is, perhaps, inclin- 

 ing to the multiple theory, but we have no real evidence. Indeed, 

 the problem still stands outside the range of scientific investigation, 

 and when Ave hear the spontaneous formation of formaldehyde men- 

 tioned as a possible first step in the origin of life we think of Harry 

 Lauder in the character of a Glasgow schoolboy pulling out his 

 treasures from his pocket — ^"That's a wassher — for makkin' motor 

 cars." 



As the evidence stands at present all that can be safely added in 

 amplification of the evoliitionary creed may be summed up in the 

 statement that variation occurs as a definite event, often producing a 

 sensibly discontinuous result; that the succession of varieties comes 

 to pass by the elevation and establishment of sporadic gi^oups of 

 individuals owing their origin to such isolated events; and that the 

 change which we see as a nascent variation is often, perhaps always, 

 one of loss. Modern research lends not the smallest encouragement 

 or sanction to the view that gradual evolution occurs by the trans- 

 formation of masses of individuals, though that fancy has fixed 

 itself on popular imagination. The isolated events to which varia- 



