1052 THE BUTTERFLIES OF NEW ENGLAND. 



its cocoon entirely out of sight of and often at a great distance from her 

 visitors. It is plain that in instances of this sort, known to every entomo- 

 logist and too numerous to mention, the sense of smell must be the sole 

 directing agent ; and since in many of these instances no odor is perceptible 

 to human sense, it is plain that there may be many odors emitted which 

 though imperceptible to us, may be all-sufficient for them. This abun- 

 dantly cx])lain8 the many cases of organs from which we can perceive no 

 odor, when in allied insects identical organs are perceptibly fragrant. 



Moreover, we have in certain specific structures in the enlarged antennal 

 club of butterflies what are plainly sense-organs supplied with nerve- 

 endings ; and inasmuch as there is no structure found in them which could 

 subserve the purpose of hearing, or indeed of any other of the senses known 

 to us excepting that of smell, it is the belief of physiologists that here are 

 situated the organs of smell in butterflies. The under surface of the anten- 

 nae of butterflies is invariably naked to a greater or less degree, and, more 

 plainly in some joints than in others, little dimples can be rcadil}' seen. It 

 is in these little pits that are situated the organs of smell ; each consists of 

 a sac-like cavity, the opening into which is often protected by cuticular 

 processes, and at the bottom of which in the hypoderm is situated a fusiform 

 body with a delicate conical ending extended free into the centre of the 

 sac, its other extremity being in direct continuation of a nervous thread. 



For myself I am inclined to attribute to butterflies as to moths an ex- 

 ceedingly delicate and high perception of odors. Any one observing their 

 action with this in view will find numerous instances in which this sense 

 certainly seems to come in play, particularly as it appears highly prob- 

 able from recent researches that the sight of these creatures is far less 

 distinct than was formerly supposed. The mere fact that the eggs of but- 

 terflies are invariably laid upon or in close proximity to the food plant of the 

 caterpillar can be explained, it seems so me, only on the supposition that 

 the creatures have the power of distinguishing such plants hy their odors. 

 If one will watch a butterfly bent upon laj'ing eggs as it flits in and out 

 among the herbage, he cannot fail to perceive the brief visit it makes to 

 plants which seem quite closely to resemble the food plant of the cater- 

 pillar, and how quickly it settles upon the desii-ed object as if it were recog- 

 nized in an instant. More than this, how unerringly it discovers the plant 

 it is in search of even if hidden beneath a canopy of entangled obstacles. 

 It acts in eveiy way as if it were scenting out the object of its quest. 



So, too, the veiy high development of scent scales of varied patterns and 

 character among butterflies indicates a direct sexual use which is the more 

 easily understood when we consider that the greater variety and brilliancy 

 of the colors of butterflies as contrasted with moths has, in all probability, 

 no sexual significance whatever. Brilliant masculine colors may possibly 

 have arisen in birds through sexual selection, but such an origin is impos- 



