The American evolutionist, T. H. Morgan, also a specialist in Mendelism, goes further, and maintains, not merely that mutations which happened to make a 'difference to the prospect of success' survived, or were selected, but that if a mutation arising from a change in the gametes was not compatible with the conditions of the animal's life at the time, it either died, or found other conditions, or adopted new habits which were adapted to the new character or structure. He takes Flat-fishes as an example, and suggests that having by mutation become asymmetrical, and having both eyes on one side, etc., the fish adopted the habit of lying on the ground on one side of its body. This is, of course, the exact opposite of the older conception: the structure of the animal has not been changed by new habits or conditions, but new habits and conditions have been sought and found in order to meet the requirements of the change of structure. The present writer, on the other hand, believes that not only are adaptive characters distinct from non-adaptive specific characters, and from non-adaptive diagnostic characters in general, but that their origin and evolution are entirely distinct and different. There are two separate problems, the origin of adaptations and the origin of species, and the investigation of these two problems leads not to one explanation common to both, but to two entirely different explanations, to two different processes going on throughout the organic world and affecting every individual and every group in classification.