406 
MR. TUFFEN WEST 
" The whole interior " of 
a really good idea of the nature of the " frog " in a horse's foot. 
the joints " bristles with elose-set minute points, the tips of which terminate at the same 
level and form a velvety surface. Now these points are the whitish bulbous extremities 
exactly answerable to those on the palms of the fly, and doubtless they answer the very 
same purpose. Only here they are set in closer array, and are a hundred times more nu- 
merous, whence we may reasonably presume a higher power of adhesion to be possessed 
by the beetle. The structure is best seen in the male, which may be distinguished by its 
smaller dimensions and by its broader feet." Two errors exist here, which, on reflection, 
would have at once occurred to the author from whom I quote. 1. As to the number 
of hairs, allowing for the different proportionate size of the part to which they are 
attached in the fly, and of a single tarsal joint of the beetle. According to the above 
assertion, this would exceed 120,000 on each joint of the latter ; the real number I have 
not computed, but it would not be difficult to obtain complete accuracy on this point : 
I believe them to be about alike on relative areas; if anything, somewhat fewer in 
number on the beetle. 2. The assertion that " a higher power of adhesion " is possessed 
by the beetle " (than by the fly) is contrary to easily ascertained facts. 
The second example of a beetle's foot which is adduced, is that of the " hand " of 
Dyticus. The parts constituting this organ are correctly described, and the proportionate 
increase in number of the holding appendages, as they diminish in size, is mentioned ; this 
latter interesting fact proves to be nearly universally the case. 
Besides the observers already cited, I might refer to numerous others who have left 
notices respecting the feet of insects, and the mode of progression of the Fly ; but as for 
the most part these observations contain nothing of real importance, I shall content myself 
with merely citing their names for the benefit of those who may wish to refer to then" 
writings. 
Homberg, Kecueil de l'Aeademie des Sciences, 1710. 
Reaumur, Memoires pour servir a l'Histoire des Insectes, vol. iv. p. 259, 1738. 
Hoesel, Entomologie, 1746-61. 
G-. Adams, senior, 1746, Essays on the -Microscope (merely a paraphrase of Hooke s 
which 
description). 
J. C. Keller, 1764, Geschichte der gemeinen Stubenfliege ; the illustrations in 
are remarkably fine. 
G. Adams, junior, 1787, Essays on the Microscope, new edition. 
And last, though not least, 
J. Lister, 1833, in some remarks on Mr. BlackwalTs observations, in which the mode 
in which the hairs of the pulvillus are employed, and the greasy marks left by each, '<■ 
clearly pointed out. The conclusion drawn by Mr. Lister from his observations is that 
the pulvilli are attached by simple adhesion of the enlarged ends of the hairs, assis 
are 
ted 
by a fluid that is probably secreted there. He also clearly describes the mode of detach- 
ment of the foot. 
My desire has been, in making this enumeration of the labours of others, to do justice 
to all parties. It will be seen in what an interesting way each successive observer ha* 
corrected some point in the statements of his predecessors, added his own contribution to 
