138 EVENINGS AT THE MICROSCOPE 



outward, so that the space covered by the bulbs of the 

 filaments is considerably greater than that of the palm 

 itself. 



Now it is evident that the bulbous extremities of these 

 soft filaments are the organs of adhesion. We notice how 

 they drag and hold, as the fly draws its foot from its 

 place, and it seems almost certain that the adhesion is 

 effected by means of a glutinous secretion poured out in 

 minute quantities from these fleshy tips. When the foot 

 is suddenly removed, we may often see a number of tiny 

 particles of fluid left on the glass where the filaments had 

 been in contact with it: but I do not build conclusively 

 on this appearance, because the fly, having been confined 

 for some quarter of an hour in this nearly tight glass cell, 

 has doubtless exhaled some moisture, which has condensed 

 on the glass; and the specks we see may possibly be due 

 to the filaments of the palms having become wet by re- 

 peatedly brushing the moist surface. Mr. Hepworth, how- 

 ever, asserts that a fluid is poured out from these filaments, 

 and is deposited on the glass, when the fly is vigorous, 

 with great regularity. He says that "when in a partially 

 dormant state, the insect does not appear to be able to 

 give out this secretion, though it can still attach itself: 

 indeed, this fluid is not essential for that purpose." 1 It 

 is asserted that the speckled pattern of fluid left on the 

 glass by the fly's footsteps remains (if breathed on) when 

 the moisture is evaporated; and hence it is presumed to 

 be of an oily nature. 



In some Beetles the joints of the foot are furnished 

 with similar appendages. I shall now show you the fore- 

 foot of a well-known insect, called by children the Bloody- 



1 "Microsc. Journal," for April, 1854. 



