330 Dr. Frederick A. Dixcy on 



mimetic systems, is liable to be carried off in this or that 

 direction as it comes under their influence. Sometimes, 

 as in the ibrms that were discussed at the beginning of 

 this piiper, we find several species, closely related to one 

 another by affinity, being- drawn away in difl'erent direc- 

 tions by the attractive power of the Miillerian groups 

 that surround them ; and the same assemblage of cases 

 illustrates the fact that a mimetic change from the original 

 form in the direction of one protected group may serve 

 as a stepping-stone for a further departure towards 

 another.* Sometiines again, as in Myluthris li/pera, M. 

 lorena, M. maleaka, and M. pijrrha, we see that in the 

 males a compromise is struck between the ordinary 

 Pierine aspect (used for flight), and a mimetic dress like 

 that of tlio female (used for repose) ; while in Pieris 

 liicusta we iind the same compromise in the male, with 

 the curious difference that hero oven the sexes of the same 

 species have been wrested apart into separate mimetic 

 relations. 



Finally, the comparison will perhaps not seem too far- 

 fetched, if the several mimetic groups, each with its own 

 type of coloration, are likened to the solar and stellar 

 systems of astronomers. Sometimes, as in the solar 

 system, there is one central body {i.e., species) dominat- 

 ing the whole, and influencing its attendant planets {i.e., 

 mimics) to an extent in comparison with which the force 

 they themselves can exercise is insignificant. At other 

 times, as in the systems of double and midtiplo stars, 

 there are bodies (^l.c., species) more nearly equal in mass 

 and importance, bound together by mutual attraction 

 into a single combination, where each one elfectively 

 controls and is controlled by the rest. Wo may even 

 push the comparison so far as to find an analogy between 

 those irregular wanderers through cosmic space which 

 from time to time get drawn within the limits of some 



* E.g.., as was pointed out above, forms like Pieris pandosia^ 

 P. lept<ili)i(>, oic, show the result of attraction by the inachia group 

 upon /Vc'/v'.s of the ordinary kind. Similarly the yellow female 

 of" /'. flciui)/)liile (ixeniplifuis the oidinary form attracted in another 

 direction, that of the (u/nu combination. Again, the last-named 

 doveloi)ment of iVe/7'.s has served as a basis for a further attraction, 

 that by IleMconius charitonia, as seen in P. viavdi 9 ; smd this latter 

 form has given scope for the influence of the altliiti group as shown 

 by /'. l„rn,la V . 



