112 



SCIENCE-GOSSIP. 



conditions that are evident in some stage or other 

 of the species that determine the super-family, 

 family, sub-family, tribe or genus, into which we 

 group the various species. It is these that make 

 us assert that the Hepialids and Micropterygids 

 are among the oldest Lepidoptera now in existence, 

 meaning thereby that they are those that have 

 undergone least change from the primitive form 

 of lepidopterous insect, although how much 

 modification they have undergone we have really 

 no conception. It is these that make us say that 

 the Sphingids and Geometrids are among the most 

 specialized of Lepidoptera. 



Useless Specific Characters. 

 This long line of ancestry, accompanied as it has 

 been by endless modifications that have taken 

 place during the aeons of time through which the 

 species and their ancestors have existed, has left 

 a very complicated facies. Among the various 

 structures and markings of the Lepidoptera (and 

 the same general facts hold good also for other 

 branches of zoology) are many that have persisted, 

 and for which now there seems to be no actual 

 use. The fact that every species has, in its long 

 ancestral past, carried at each stage of its evolu- 

 tion various peculiar structures and markings 

 that distinguished it from its then allies and were 

 useful to it at the time, and so back through all 

 time during which insects have existed as such, or 

 even further back to the first dawn of life, does not 

 seem to be appreciated by many naturalists. That 

 these markings and structures should in some 

 instances persist in a modified form when they 

 have ceased to be directly useful, although not 

 hurtful, to the species in its present form, has 

 raised in the minds of some naturalists a suspicion 

 that some apparent specific characters are not 

 useful to their possessors. From this, some have 

 gone on to assert that certain of these characters 

 never have been useful to the species. If one will 

 carefully consider the development of species in 

 time, if one will consider our absolute ignorance of 

 these early forms, except such as we can gather 

 from analogy by the closest study and comparison 

 of various species, it is surely somewhat unsafe, if 

 not illogical, to make such an assertion. 



Spontaneous Variations and Natural 

 Selection. 



It is quite true, as Romanes has pointed out, 

 that Darwin himself believed that every " slight 

 individual difference, as well as more strongly 

 marked variations which occasionally arise," had 

 " an efficient cause," and that " if the cause were to 

 act persistently, it is almost certain that all the 

 individuals of the species would be similarly 

 modified." Romanes took his stand on the 

 principle here enunciated, and attempted to 



maintain the position of Darwin with regard to 

 this and similar statements. Wallace, however, 

 has shown that this reasoning can only be true 

 when the same cause acts persistently on identical 

 materials under identical conditions. He has also 

 further pointed out that the very theory of natural 

 selection is based on the fact that the materials, 

 i.e. the individuals or species, are not identical, 

 but that they vary indefinitely, and in many 

 directions even under closely similar conditions. 

 He asks : " How, then, can any external or 

 internal cause produce an identical result— a 

 definite new variation — in all the individuals of a 

 species, born as they are of varying parents, of 

 different ages, and subject to ever fluctuating 

 conditions?" The endless variation of almost 

 every species of insect, in a more or less marked 

 manner, re-echoes Wallace's question ; and I can 

 see no other conclusion than that natural selection 

 has chosen and intensified variations that have 

 occurred independently in the species, and modified 

 such into paths that have proved useful to the 

 species when any striking change in the environ- 

 ment has taken place. 



Characters Utilitarian. 



I quite agree with Wallace that the selection of 

 all variations, whether now exhibited as class, 

 family, tribal, or generic characters, has been 

 brought about by utility to the species, and 

 perfected- by natural selection. We differentiate 

 our classes, families, tribes and genera, on the 

 remnants of previous elements of utilitarianism. 

 The active utilities are more conspicuous to us, 

 are more prominently brought to our notice, 

 by the differences existing between the species 

 and its local race, between species and species, 

 and so on throughout the whole scale ; for, if we 

 may so term it, the differences between two 

 families, or classes, are only the accumulated 

 differences which have existed, and in a mea- 

 sure persisted, between the endless specific 

 forms which have been developed and have died 

 out since the representatives of the now dis- 

 tinct classes formed but a single species. The 

 problem of the utility of family, tribal and 

 generic characters is all included, then, in the 

 consideration of the utility of specific characters ; 

 for, in the species, the useful differentiations 

 have been completed, and are not in a state of 

 doubt, as they are between a species and its 

 local races. At the same time, the consideration 

 of the utility of specific characters leaves the 

 problem shorn of the secondary and tertiary (and 

 so on, ad infin.) considerations as to disuse and 

 subsequent modifications that at once accumulate 

 when one commences to study the same problem 

 when applied to genera, tribes, families, etc. 

 (To be continued.) 



