210 INITIATIVE IN EVOLUTION 



The Fly-shaker Muscle. 



The panniculus carnosus, of which the facial muscles are part, 

 is a great system of musculature found in various animal forms, and 

 it furnishes a field for studj r of the evolution of the indifferent and 

 the initial stages of the formation of a muscle. This is a servant 

 of the brain in a more indirect manner than the facial muscles, 

 but it, too, arises in obedience to the integrative action of the brain. 

 The early specialisation of it need not be considered here. It may 

 be considered unwarrantable to claim the great Fly -shaker muscle 

 of Ungulates as an indifferent structure, but the arguments by 

 which the Pan-Selectionist would annex it to his sceptre, as a 

 triumph of the minute care of the organism by selection, rest only 

 on the assumption that he knows how it has become an adaptation 

 to the life of its possessors. This is now more than it used to be a 

 matter of opinion since the publication of Professor Bateson's 

 revolutionary Materials, and others beside he have reserved to 

 themselves the liberty of doubting the accepted explanations by 

 the tangled path of adaptation. The statement of Weismann, 

 " Everything is adapted in animated nature " was necessary to 

 his theory of germinal selection, but it admits of extensive and 

 numerous exceptions in view of the fact that so much of adaptation 

 is partial and imperfect. If he had said that every organism as a 

 being is adapted he would have been nearer the truth, but that 

 every tissue and part of an organism is adapted is demonstrably 

 untrue. A large number of organisms, themselves apparently 

 well adapted, flourish well enough and reproduce their kind in 

 spite of faulty and rudimentary tissues and parts. If it were not 

 so we should have seen little of progress except what come under 

 the laws of genetics, — a distributional matter. Even the super- 

 Geddes could not distribute what was not there, for he could not 

 deal with raw materials and change them by a fairy wand into 

 manufactured articles. In the great field of domesticated plants 

 and animals man has to find not only some mutation or some 

 dominant strain and breed it to his will, but to cultivate the domestic 

 qualities of animals and employ cultural conditions for plants. 

 There is doubt expressed as to the length of time or numbers of 

 generations during which these cultural conditions can extend, but 

 Professor Thistleton Dyer many years ago made the remarkable 

 statement as to plants : — " While specific stability under constant 

 conditions appears to be the rule in nature, it is widely different 

 in cultivation. Whenajjlant is brought under cultural conditions 

 it maintains its type for some time unaltered, then gives way 

 and becomes practically plastic. From my experience at Kew, 



