404 MR. TUFFEN WEST ON THE FOOT OF THE FLY. 



Mr. Jolin Hepworth (1854) * also, nearly at the same time, and in near neighbonrliood 

 vnih the last-named author, was repeatedly examining the feet of some large flies, and 

 other insects, in the living state. The terminal enlargements of the " hair-like appendages" 

 were now for the first time clearly represented : their mode of action is compared with that 

 of the suckers of the male Dyticus. The general form of the flaps, their thickened base, 

 and thinned-oi\t margins were described from several flies, as they appear when viewed 

 under the compound microscope. The scale-like hairs occasionally found on their upper 

 surface are also noted, as well as, from independent observation, the marks left on glass 

 by the " trumpet-shaped extremities of the appendages to their flaps." A portion of the 

 edge of the flap, which had got turned in mounting, " is figured," which shows the suckers 

 more distinctly. 



The descriptions are brief to a degree which renders it difficult sometimes to understand 

 the exact meaning of the author ; this is, however, remedied, in some degree, by the 

 abundance and general clearness of the illustrations ; in remarking on which, we are told 

 that "the parts are too obvious to require description" (!). 



Mr. Hepworth's opinions possess much value because they were foimded on independent 

 observations, with the microscope, on the parts as they appear during life, in action and 

 in repose, and were repeated frequently and with care. 



Mr. Tyrrell (1855) t suggested the use of the " hooJes on the feet of flies," as " intended 

 not to attach the fly to anything, but to be used as fulcra or props which the fly can j)ush 

 against when it wishes to detach the cushions." Careful investigation proves that they 

 are used for the purpose of detaching the foot ; biit it was a very imperfect view of the 

 matter to think that tliis was their only use. 



Mr. Hepv/orth (1855) J in replying to remarks, in continuation of the above, which 

 evince a misapprehension of his views, takes occasion to go into some detail respecting his 

 opinions. He says that each sucker is under the influence of the will, and adduces some 

 valuable observations by Ecker, on contractile structures in their earliest manifestations, 

 as representing exactly what he wishes to express in this matter. An objection to the 

 viscid-secretion theory, when carried to the excess it was by some of its advocates, and 

 which Avill readily occur to the student, is well put. "If," he says, "the foot were 

 to be attached for some time (twenty or thirty minutes, as I have often seen it) to the 

 same spot, it would get so firmly fixed that, if forcibly raised by the leverage of the hooks, 

 these exceedingly delicate structures " (the " hair-like appendages ") would be destroyed. 

 A computation is then given of the number of " suckers " on " the flap of the Blow-fly," 

 which I believe to be correct when the number allowed for " the triangular part, extending 

 for attachment up to the leg " has been deducted. This deduction is necessary because none 

 of these organs are present on a part which can never be applied to any surface for the pur- 

 pose of holding to it ; with this allowance, the number will be about 12,000 on each foot 

 of the fly in question. The paper continues, by explaining a " diagram," of " Hairs from 

 the pad of the foot of a small Curculio beetle ; they expand into the form of a trumpet, and 

 where the expansion commences they appear corrugated, and the corrugation is continued 



* Quarterly Journal of Microscopical Science, vol. iii. 



t Ibid. vol. iv. p. 230. X Ibid. P- 312. 



