24:6 .THE MICROSCOPE AND ITS REVELATIONS. 



men (the body of the insect being curved downwards); and, being guided 



into the slit by a pair of small hairy feelers, there deposits an egg. * 



Many other insects, especially of the order Diptera, have very prolonged 

 ovipositors, by means of which they can insert their eggs into the integu- 

 ments of animals, or into other situations in which the larvae will obtain 

 appropriate nutriment. A remarkable example of this is furnished by 

 the Gad-fly (Tabanus), whose ovipositor is composed of several joints, 

 capable of being drawn together or extended like those of a telescope, and 

 is terminated by boring instruments; and the egg being conveyed by its 

 means, not only into but through the integument of the Ox, so as to be 

 imbedded in the tissue beneath, a peculiar kind of inflammation is set-up 

 there, which (as in the analogous case of the gall-fly) forms a nidus appro- 

 priate both to the protection and to the nutrition of the larva. Other 

 insects which deposit their eggs in the ground, such as the Locusts, have 

 their ovipositors so shaped as to answer for digging holes for their recep- 

 tion. The preparations which serve to display the foregoing parts, are 

 best seen when mounted in Balsam; save in the case of the muscles and 

 poison-apparatus of the sting, which are better preserved in fluid or in 

 glycerine-jelly. 



642. The Sexual organs of Insects furnish numerous objects of 

 extreme interest to the Anatomist and Physiologist; but as an account 

 of them would be unsuitable to the present work, a reference to a copious 

 source of information respecting one of their most curious features, and 

 to a list of the species that afford good illustrations, must here suffice. 2 - 

 The eggs of many Insects are objects of great beauty, on account of the 

 regularity of their form, and the symmetry of the markings on their sur- 

 face (Fig. 437). The most interesting belong for the most part to the 

 order Lepidoptera; and there are few among these that are not worth 

 examination, some of the commonest (such as those of the Cabbage butter- 

 fly, which are found covering large patches of the leaves of that plant) 

 being as remarkable as any. Those of the Puss- moth ( Cirura vinula), 

 the Privet hawk-moth (Sphinx ligustri), the small Tortoiseshell butterfly 

 ( Vanessa urticce), the Meadow-brown butterfly (Hipparchiajanira), the 

 Brimstone-moth (Rumia cratmgatd), and the Silkworm (Bomlyx mori), 

 may be particularly specified: and from other orders, those of the Cock- 

 roach (Blatta orientalis), Field Cricket (Acheta campestris), Water-scor- 

 pion (Nepa ranatra), Bug ( Cimex lectularius), Cow-dung-fly (Scatophaga 

 ster cor aria), and Blow-fly (Musca vomitorid). In order to preserve these 

 eggs, they should be mounted in fluid in a cell; since they will otherwise 

 dry up and may lose their shape. They are very good objects for the 

 ' conversion ^of relief ' effected by Nachet's Stereo-pseudoscopic Binocular 

 ( 38). 



643. The remarkable mode of Reproduction that exists among the 

 Aphides must not pass unnoticed here, from its curious connection with 



1 The above is the account of the process given by Mr. J. W. Gooch; who has 

 informed the Author that he has repeatedly verified the statement formerly made 

 by him (" Science Gossip," Feb. 1, 1873), that the eggs are deposited, not as origi- 

 nally stated by Reaumur, by means of a tube formed by the coaptation of the 

 saws, but through a separate ovipositor, protruded when the saws have been with- 

 drawn. 



2 See the Memoirs of M. Lacaze-Dutheirs, ' Sur 1'armure genitale des Insectes,' 

 in "Ann. des Sci. Nat.," Ser. 3, Zool., Tomes xii., xiv., xvii., xyiii., xix.; and M. 

 Ch. Robin's " Memoire sur les Objets qui peuvent etre conserves en Preparations 

 Microscopiques " (Paris, 1856), which is peculiarly full in the enumeration of the 

 objects of interest afforded by the Class of Insects. 



