Chap, XIII. EEVEKSION. 23 



have not striped legs, — and the hybrids have conspicuous 

 stripes on their legs and even on their faces, all that can be 

 said is, that an inherent tendency to reversion is evolved 

 through some disturbance in the organisation caused by the 

 act of crossing. 



Another form of reversion is far commoner, indeed is almost 

 universal with the offspring from a cross, namely, to the 

 characters proper to either pure parent-form. As a general 

 rule, crossed offspring in the first generation are nearly inter- 

 mediate between their parents, but the grandchildren and 

 succeeding generations continually revert, in a greater or 

 lesser degree, to one or both of their progenitors. Several 

 authors have maintained that hybrids and mongrels include 

 all the characters of both parents, not fused together, but 

 merely mingled in different proportions in different parts of 

 the body ; or, as Naudin 50 has expressed it, a hybrid is a 

 living mosaic- work, in which the eye cannot distinguish the 

 discordant elements, so completely are they intermingled. 

 We can hardly doubt that, in a certain sense, this is true, as 

 when we behold in a hybrid the elements of both species 

 segregating themselves into segments in the same flower or 

 fruit, by a process of self-attraction or self-affinity; this 

 segregation taking place either by seminal or bud-propagation. 

 Naudin further believes that the segregation of the two 

 specific elements or essences is eminently liable to occur in 

 the male and female reproductive matter ; and he thus 

 explains the almost universal tendency to reversion in succes- 

 sive hybrid generations. For this would be the natural 

 result of the union of pollen and ovules, in both of which the 

 elements of the same species had been segregated by self- 

 affinity. If, on the other hand, pollen which included the 

 elements of one species happened to unite with ovules includ- 

 ing the elements of the other species, the intermediate or 

 hybrid state would still be retained, and there would be 

 no reversion. But it would, as I suspect, be more correct 

 to say that the elements of both parent-species exist in every 

 hybrid in a double state, namely, blended together and com* 



50 'Nouvolles Archives du Museum/ torn. i. p. 151. 



