4l06 MR. TUFFEN WEST ON THE FOOT OF THE FLY, 



a really good idea of the nature of tlie " frog " in a horse's foot. " The whole interior " of 

 the joints " bristles ^nith close-set minute points, the tips of Avhich 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 arese ; 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 their 

 writings. 



Ilomberg, Recueil de I'Academie des Sciences, 1710. 



E-eaumur, Memoires pour servir a I'Histoire des Insectes, vol. iv. p. 259, 1738. 



Roesel, Entomologie, 1746-61. 



G. Adams, senior, 1746, Essays on the Microscope (merely a paraphrase of Hooke's 

 description). 



J. C. Keller, 176 i, Geschichte der gemeinen Stubenfliege; the illustrations in which 

 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. Blackwall's observations, in which the mode 

 in which the hairs of the pulvillus are employed, and the greasy marks left by each, are 

 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, assisted 

 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 has 

 corrected some point in the statements of his predecessors, added his omti contribution to 



