HAEDWICKE'S SCIENCE-GOSSIP. 



inatiou from one to auotlier, ask for help, and give 

 orders, is borne out by the observations of many 

 dihgent students of both the tribes. 



That in many cases they are admirably adapted as 

 organs of touch or feeling would appear to be the 

 case from the great number of joints, their extreme 

 delicacy, and the easiness of movement in every 

 direction. Many insects, when at rest, fold back 

 the antenna;, so as to conceal them, but as soon as 

 they begin to move, the antennae are thrust forward, 

 the parts are separated widely, and while in some 

 they are vibrated from side to side, in others, as in 

 some species of wood lice (as observed by Ivirby and 

 Spence), they are used as organs of touch. It has 

 been urged that they cannot well be organs of touch, 

 on account of the hard horny character of their 

 outer surfaces, and that this function is performed 

 by another set of organs, — the pa/pi. 



Many naturalists incline to the idea that they are 

 the organs of hearing. Now it is generally conceded 

 that in the Crustacea, especially the higher ones, the 

 organs of hearing are situated at the base of the long 

 external pair of antennce, and, as in the case of the 

 crayfish, consist of a hollow cylindrical process, 

 closed internally by a drum or thin membrane, behind 

 which is a vesicle filled with fluid, which receives 

 the termination of a nerve ; but the organ of smell, 

 as has been principally observed with crabs, consists 

 of cavities lined with a mucous membrane, situated 

 at the base of the inner pair of anteaure, and pro- 

 tected externally by fine bristles. 



Many observers have noticed that, if a noise is 

 made, the antenna; of some insects are turned in 

 the direction of the part from which the noise comes. 

 This has been observed in the case of the longicoru 

 beetles, grasshoppers, and crickets, which, when 

 suddenly surprised by a noise, have been seen to 

 stretch out their long antennae and stand, as it were, 

 attentively listening for the sound. Rennie mentions 

 a green grasshopper inclining its antennae to the 

 rustle of a piece of paper under the table on which 

 it was placed, and bending one of them in the direc- 

 tion of the sound. 



On the other hand, many circumstances seem to 

 prove that insects possess a very acute sense of 

 smell. It has been observed in "Episodes of 

 Insect Life" that "no flocks of vultures can be 

 directed more unerringly to their revolting prey by 

 its odours from afar than certain insects, such as 

 dung-flies and carrion beetles, whose corresponding 

 office is to assist in ridding the earth of offensive 

 objects." That it is the sense of smell which 

 •directs the blow-fly to the deposition of the larva; 

 is shown by the fact that she has laid them on sta- 

 pelias, a carrion-odoured hothouse plant, and on 

 silk with which tainted meat had been covered. 

 Equally keen-seented are butterflies and bees; the 

 latter have flown miles in the direction of particular 

 flowers, whose odour had been wafted by the wind. 



while the former have alighted from a considerable 

 height on their favourite flowers. Then, as is well 

 known to lepidopterists, night-flying moths are 

 attracted from long distances by anointing the 

 trunks of trees with sugar or treacle, and this, we 

 should think, by the sense of smell alone. 



Again, as we have stated on several occasions, 

 the males of some species of moths are attracted by 

 the females under such conditions as to lead to the 

 idea that either the sense of smell is wonderfully 

 acute, or that they possess some sense not yet deter- 

 mined by physiologists. Placed in boxes either 

 carried in the coat-pocket, put in a basket, or shut 

 up in a leather bag, the perceptive faculty has been 

 so strong in the male that they have been seen 

 flying over the top of a wood at least 300 yards off- 

 Nay more, we have had them settle upon ourselves 

 when the box containing the female was no longer 

 in the pocket. Our idea is that some of the (to us) 

 imperceptible scent clung to our garment. 



Among the authorities inclining to the idea that 

 the antennas are the organs of hearing are Sulzer^ 

 Scarpa, Schneider, Rockhauser, Burmeister, Carus, 

 Oxen, Kirby and Spence, Newport, and Hicks : the 

 last named we have more particularly to refer to 

 presently. On the side of those who consider them 

 organs of smell are Reaumer, Lyouet, Robineau, 

 Desvoidy, Kiister, Erichsou, and Vogt. 



It might be asked — Has the microscope done 

 anything, and if so, what, in solving these difficul- 

 ties ? Newport in ISol (" Transactions of the 

 Entomological Society," vol. ii. p. 229) found all 

 the joints, except the second, of Ichneumon Atropos 

 perforated all round by very minute holes. He 

 observed also tracheae passing up the whole length 

 of the antennte, and giving ofl" branches at every 

 joint, and which, as he considered, communicated 

 with the holes in the wall of the antennae. Of this, 

 though, he was not quite certain. He states that 

 thesamestructurecxisted in most setaceous antennae. 

 E. E. Erichson published at Berlin, in lSi7, his 

 "Dissertaito de Eabrica et Usu Antennarum in 

 Insectis," in which he enunciated these laws: 1st. The 

 wall of the antenna; in insects is by no means solid, 

 but perforated by numerous openings. 3nd. These 

 openings are closed on the inner side by a mem- 

 brane. 3rd. The openings in the antennae of differ- 

 ent insects are arranged in different ways. He also 

 shows that these openings are never found in the 

 basal joint. He considered the numerous hairs 

 found in the antenna;, between the pores or open- 

 ings, protected them from extraneous bodies, and 

 that the pores were organs of smell, because, " as 

 the olfactory organs of the higher animals are moist 

 membranes, in order that the odorous particles may 

 be dissolved by the humour secreted, in the same 

 way these membranes perform the same office, are 

 protected by the downy hairs, and kept moist by 

 them." xVuother reason why he considered them 



