176 SELECTED NOTES. 



is in free communication with the outer air through an opening in 

 the forehead immediately above the antennae. The outer surface 

 is covered wi^h numerous papillae. When the folds are brought so 

 close together that the papillae interlock, they always enclose some 

 air, thus preventing any adhesion of the surfaces, which might be 

 the case if the surfaces of the folds were smooth and moist. By 

 this means an equable pressure is maintained on the brain and 

 other organs. Some years smce (1887 or 1888) I read a paper 

 before the Sheffield Microscopical Society on the " Frontal Sac." 

 This was published in Science Gossip without my consent and con- 

 sequently without my signature. 



The third slide shows sections of the antennae. These sec- 

 tions are mostly cut through the second and third joints, the first 

 joint not being in the same plane. Exteriorly the third joint is 

 covered with two kinds of pigmented hairs. The finer and 

 smaller appear to be nothing more than clothing ; but the larger 

 ones are hollow, their lumen continuing through the chitinous wall 

 of the joint. Epithelium lines the interior of the joint, the ends 

 of the cell being drawn out, and projects into the lumen of the 

 hairs. This is distinctly seen in thin sections, in which the epi- 

 dermis became somewhat detached from the epithelium during the 

 manipulation of the section. From the nerve numberless fibres 

 are seen to enter the epithelium lining, but I have been unable to 

 trace them any further. 



By using a more suitable stain, the nerve-fibres may possibly 

 be traced through the epithelium, or the epithelium may be 

 endowed with the same conducting power as the nerve-fibre. From 

 this rich supply of nerve matter, it is pretty clear that the large 

 hairs must be the seat of some sensation, but what sense they 

 represent is very difficult to prove by experiment, because another 

 sense-organ is intermingled with them. It is highly probable that 

 these are tactile organs, though this term is very vague, for it 

 implies the sensation of either cold or heat, humidity, or touch, 

 etc., and for this reason I am of opinion that further proof is still 

 required. 



The most highly developed tactile hairs are those on the lobes 

 of the proboscis, where they end in a large bulb in immediate 

 connection with the nerve. By their position they are undoubtedly 



