 The difficulties in Darwin’s arguments that had emerged by 1866 were highlighted in a lengthy and telling critique in 1867 by the Scottish engineer Henry Fleeming Jenkin (1833–85) (typically Fleeming Jenkin). Using an argument previously raised in the 1830s by Charles Lyell against Lamarck, Fleeming Jenkin cited empirical evidence from domestic breeding that suggested a distinct limitation on the degree of variation, and denied that selection upon this could be taken to the extent assumed by Darwin (Fleeming Jenkin 1867; Hoquet 2013). Using a loosely mathematical argument, Fleeming Jenkin argued that the effects of intercrossing would continuously swamp deviations from the mean values of characters and result in a tendency of the variation in a population to return to mean values over time. For Fleeming Jenkin, Darwin’s reliance on continuous additive deviation was presumed to be undermined by this argument, and only more dramatic and discontinuous change—something Darwin explicitly rejected—could account for the origin of new species.