(J DONALDSON BODINE. 



remainder of the substance found in the interior is the blood, which 

 freely bathes the tissues and provides for their nourishment. 



The chitinous covering of the antennae is of the same general 

 character as that of the body, but it is neither so thick nor so com- 

 pact in structure. It lies just ectad of the layer of dermal cells 

 making up the limiting stratum of the vital tissues of the insect and 

 is doubtless formed by the secretion from those cells. Its surface is 

 fre(|uently marked off into more or less nearly hexagonal areas. Fig. 

 34, which, in some cases, are said by various authorities to corre- 

 spond to the underlying layers of cells. They are limited by very 

 thin, continuous ridges of chitin sometimes, e. g. in Notolophus lea- 

 costigma, Fig. 30, raised as high as 3 m. from the surface. In other 

 cases there is an external layer of overlapping j^lates which may or 

 may not mark the outlines of the dermal cells. Figs. 38 and 39. The 

 surface of the plates is often broken up into fine points and ridges 

 which frequently obscure the outlines of the plates themselves. In 

 still other forms there is a covering of fine hairs which are really 

 simple projections of the chitin itself and quite different from the true 

 hairs described below. Fig. 40. 



The many structures found on the antenme of the Le})idoptera 

 which have originated from the interior may all be regarded as 

 modifications of a simple hair. Each has its origin in a hypodermal 

 cell, and therefore is connected with the interior through a pore- 

 canal. The simplest form is that of a simple, protective hair, situ- 

 ated at the ectal end of a pore-canal. In the structure of the chi- 

 tinized parts it differs slightly, if at all, from the sense-hair described 

 later, but it lacks any connection with the vital tissues. Whether 

 it is an imperfect form of sense-hair, or whether it is in the condition 

 best adapted to the function it has to perform, is a question Ave are 

 unable to answer. 



A simple ffattening out of a hair, followed by some corresponding 

 changes in the secondary details of structure, would give the type 

 of a scale. These also arise from a hypodermal cell, though in the 

 imago the connection is lost. Fig. l(j shows the position and manner 

 of insertion of the scales. The pedicel, or stalk, is set in a goblet 

 shaped cell lying in the chitin with its long axis nearly perj)endicular 

 to the surface, but pointing slightly distad. The bottom of the cup 

 is at the end of a pore-canal, but there is no evident vital connection 

 with the interior. When the scale is extracted, or has fallen out, 

 the insertion-cups have the appearance of two externally tangent, or 



