Tongue of the Honey -Bee. 287 



of the numerical aperture to i " expresses how much greater is the 

 number of rays admitted by the new objectives, over that number 

 which /'// air would fill a complete hemisphere, or which would 

 be admitted by an imaginary dry objective of 180° aperture." 



The power of resolution, by strictly central illumination, is ex- 

 pressed by D = ^ — ; in which D = the distance between the 

 sin. w 



lines of a finely marked object and / = the wave-length of the 

 light. 



The comparison of the resolving power of dry and immersion 

 lenses, or objectives working in any way, may be made by the 



equation: D:D' = ^^ — :-^-^ — ,^=^sin. to': sin. w for central light, 

 sin. 7V sin. IV 



or when the same immersion fluid is used, n being the same in the 

 two cases, D:D'=a':^. 



The slightly oblique rays which come from the mirror in its 

 axial position, render this comparison not strictly correct for ordi- 

 nary conditions of work. 



THE STRUCTURE OF THE TONGUE OF THE HONEY- 

 BEE. 



BY J. D. HYATT, PRESIDENT N. Y. MICROSCOPICAL SOCIETY. 



{^Received June 2jd, 1S79.) 



A careful examination of the so-called tongue, or lingua, of the 

 honey-bee, coupled with a study of the literature relating to the 

 subject, will serve to impress the reader with the fact that no sub- 

 stantial progress can be made in adding to our store of knowledge, 

 unless our conclusions are drawn from what we observe, and 

 are not influenced by the diction of authority. As in the present 

 instance, it often happens that opinions, which have held their 

 sway for years over those whose ability as competent observers is 

 not to be questioned, can be traced back to their origin in careless 

 work or mere suppositions. 



A comparison of the tongue itself with the descriptions given 

 in the works of the most celebrated entomologists and micro- 

 scopists, will afford a more curious instance of disagreement among 

 doctors, on the one hand, and implicit reliance upon authority, on 

 the other, than can be found outside the limits of theological dis- 

 cussion. 



