20 . NATURAL SCIENCE [January 



To the Freucli school, to which we owe so much which has 

 made Entomology attractive, we are moreover indebted for that 

 divorcement of the butterflies and moths which is pronounced by 

 the terms Ehopalocera and Heterocera. Convenient as these terms 

 may be to designate what is a rough and surface grouping, we must 

 always be led to reject them as indicating, by means of categorical 

 names, a structural difference greater than really exists. In coining 

 these titles M. Boisduval stepped into the slippers of M. Dvimeril, 

 and has since found imitators who have invented for us the addi- 

 tional names of Nitrocera or Grypocera. All this brilliant play at 

 making systems, without weighing all the results, fascinates many, 

 and among these also Mr Scudder, who remains among the Suspensi 

 and Succincti, weaving in an additional original observation on the 

 ' shrouds ' of the Involuti, and believing for ever that upon these 

 threads hangs the history of the butterflies. It is almost a pity 

 that we are compelled to remember that systems and categories are 

 but part of the machinery of science, and that when they over- or 

 under-do their appointed work (which is here to designate the affini- 

 ties of organisms) they should in reason be changed or even swept 

 away. 



At what time we may imagine the primeval and colourless lepidop- 

 terous caterpillar to have left its hidden home in the stems and leaves 

 of plants and emerge into the open, here, under fresh conditions, 

 taking up the struggle for existence, and dodging the effects of its 

 difficulties by adapting itself to them, thus finding in the conflict the 

 way for the endless variation we find in the coloured larvae of to-day 

 — ^at that time, also, did tlie primeval caterpillar bring with it, of 

 necessity, the habit of spinning silk to provide for the safe repose of 

 the chrysalis. This protection would naturally vary with the sur- 

 roundings. Impeded by circumstance, subject to be thwarted and 

 turned aside by different objects and new conditions blocking the 

 fresh roads of travel, the habit of spinning would express itself 

 unequally, the old fashion displayed would become modified, at times 

 the original custom might even altogether fall away. And this is 

 what we see — cocoons of all sizes and consistencies, to the Noctuid 

 fastening together grains of sand with silky saliva. Even now the 

 individual spinning larva, forcibly prevented from completing its 

 web, or from attaching itself, will transform without protection, and 

 trust to fate to live and become a butterfly. So that the mode of 

 spinning is seen to be in itself secondary and auxiliary merely, and 

 we can understand how identical or similar fashions might appear 

 upon independent phylogenetic lines.^ Now", however the fashion of 



^ Among the Bombycides, the Laehueidae spin a cocoon, the nearly related Craterony- 

 gidae pupate nakedly in the ground. My friend, Prof. Dr Pabst, writes from Chemnitz 

 of a certain larva of the cocoon-making Euthri.v potaforia, that it transformed nakedly 

 upon the surface, without spinning a thread, yielding in due time a normal imago. 



