66 THE CAUSES WHICH PROPAGATE 



the antennae auditory (Plate VI., Fig-. 3). He describes the 

 pores, j?;, as inchiding a fluid and severally closed by a membrane, 

 sometimes thin and sometimes thickened and raised to a hair-like 

 eminence, while a nerve, n, entering the antennae sends a branch 

 to each, which ramifies on its inner side. 



Sir John Lubbock, in his volume o£ " Scientific Lectures,''^ 

 published in 1879, notices these structures in the antennae of 

 ants as " certain curious org-ans which may perhaps be of an 

 auditory character. ^^ He says : " There are from ten to a dozen 

 in the terminal segment of the small yellow Meadow Ant, and 

 indeed in most of the species which I have examined, and 

 one or two in each of the short intermediate segments. These 

 org'ans consist of three parts — a small spherical cup opening' to 

 the outside, a long narrow tube, and a hollow body shaped like 

 an elongate clock-weight.'''' It should be remarked, however, 

 that the author has previously stated his conviction that an 

 organ of smell is located in the antennae of ants, and he details 

 how they can be arrested by a cameFs-hair pencil scented with 

 lavender-water, or how an antenna was withdrawn when this 

 nostrum was presented to its tip. 



Then, finally, we have in immediate relation to muscular 

 contraction a specialised sense of touch resident in the mandibles, 

 palpi, filiform antennae, or fore tarsi, which with the anal appen- 

 dages take masculine modifications for the purpose of securing 

 the female in the chase. Thus the males of beetles are recog- 

 nisable and often distinguished by the number of dilated or 

 flattened joints of the tarsi ; and in the aquatic beetles such 

 modifications sometimes assume the form of conspicuous suckers, 

 and their females have fluted elytra to increase the hold. 

 Singular dilatations of the feet are likewise found in the males 

 of the little wasps Crabro, an Alpine grasshopper, and certain 

 small black flies, Hilaria (Plate I., Fig. 8). But this sexual 

 dilatation must not be confounded "with a notch and scale on the 

 fore tibiae, which, comparable with the comb on the claw of the 

 Goatsuckers, is used by butterflies, moths, and some beetles to 

 clean their antennae, which are repeatedly drawn out between 

 the two as a seamstress passes the thread she is about to wax 

 between the thumb and fore-finger. Other kinds of insects 

 that want this modification substitute their mandibles, as the 



