180 Mr. W. Stone on Moult 



of a species cliangcs its pluinag:c, but liaving proved a 

 reasonable uunriber of cases, may we not count our inference 

 legitimate ? All scientific reasoning is by such methods. 

 Furthermore, with the change by means of moult proven in 

 so manj' birds, Avhy should we seek to demonstrate that such 

 a wonderful phenomenon as the alleged ''change of pig- 

 ment^' should also take place in the same species? especially 

 since many of the details of such a change as set forth by its 

 advocates are at A'ariance with what we know of the histology 

 of the feather. 



On Mr. Bonhote^s line of argument we might as well 

 claim that although we know that a large number of crabs 

 increase in size only at dt^fiuite periods when the old shell 

 has been shed, nevertheless this does not jjvove that some 

 individual crabs do not go on growing continuously. I fear, 

 however, that earcinologists would regard this as an un- 

 necessary hypothesis and quite unworthy of serious con- 

 sideration. Furthermore, they would hardly consider the 

 existence of a series of crabs of graded size as proof oi this 

 method of growth. A series of particoloured feathers, how- 

 ever, is supposed to prove the alleged change of pigment ! 



Is it not really the reluctance to overthrow a theory 

 Avhich has been held so long that unconsciously prejudices 

 the adherents of the direct colour-change theory ? 



I therefore once more earnestly refer those who may wish 

 to investigate this subject to our former papers, and for the 

 present merely intend to consider the spring moult of one 

 form. As Mr. Bonhote suggests that I should extend my 

 studies to the LimicuJae, we will take as our example the 

 Sanderling [Ca/idris arenarid), a peculiarly appropriate 

 species, since it is common to both sides of the Atlantic, and 

 is known on both by the same technical name ! 



The arguments of the colour-change advocates, so far as 

 this bird is concerned, are well set forth by Mr. J. G. Millais, 

 in 'The Ibis' for Oct. 1896, p. 451, and on plate x. he 

 illustrates his theory by feathers taken from birds shot in 

 March (a grey feather), April (one with a dusky centre). 

 May (a blackish feather with white tip), and June (a similar 



