INSECTA. 



993 



Fig. 439. 



Female organs of generation of Athalia centifoliqe. 

 (Prize Essay.) 



also absent between the bag and the base of the 

 ovipositor, so that the fluid is forced directly 

 from the bag at the moment it is employed. 

 There is a somewhat similar structure in the 

 Hornet, although the vessel between the bag 

 and sting is present as in the bee. Burmeister 

 has suggested that the poison-gland may per- 

 haps be an urinary organ, but the circum- 

 stance of the fluid contained in it being em- 

 ployed by the insect to inject into the cavity 

 in which it deposits its ova, seems opposed to 

 this opinion, although that of its being em- 

 ployed by the bee as a means of defence may 

 be favourable to it. The nature of this fluid 

 is distinctly acid, as remarked by Dr. Bevan 

 in the honey-bee, and as found by ourselves in 

 several instances. The vaginal aperture at the 

 base of the ovipositor forms the external orifice 

 .of the common oviduct or proper laying tube 

 (e). This in some instances is simply a di- 

 lated orifice, the internal lining of which is 

 .continuous with that of .the internal part of the 

 ovipositor. This common oviduct is either a 

 simple, straight, uniform tube, or in some in- 

 stances is a little dilated laterally into pouches, 

 in which are received the lateral appendages of 

 the male organ, as in Melolontha. At its 

 termination the common oviduct divides into 

 or rather receives two separate tubes (d), 

 one from each side, analogous to the efferential 

 vessels of the male organs. On the upper 

 surface of the common oviduct, there are 

 appendages that vary in number from one to 

 five. The chief of these, the spermatheca (f), 

 alone exists in Athalia. It is into this sac that 

 the fluid of the male is ejected during co- 

 pulation. Audouin states that the male organ 

 is projected into it. We have invariably found 

 this vesicle, which is exceedingly large in Mcloc, 

 filled with white, opaque, seminal fluid after 

 connexion with the male, previously to which 

 time we have as invariably found this vesicle 

 -empty. This appendage is simple in many of 



"'OL II. 



the Orthoptera as well as in Hymenoptera, but 

 in some other species there are also additional 

 vesicular appendages which have been de- 

 scribed as secreting a glutinous fluid. In all in- 

 stances these are attached to and pour their con- 

 tents into the common oviduct, through which 

 the eggs pass to be deposited. In the middle 

 line, at the union of the oviducts, are situated 

 the terminal ganglia of the nervous cord 

 (10, 11), when the cord is extended to the 

 posterior part of the abdomen. But when this 

 is not the ease, and the nerves simply radiate 

 from the thorax into the abdomen, the terminal 

 pair of nerves still pass in a corresponding 

 direction over the union of the oviducts, thus 

 always occupying a position between the organs 

 of generation and the termination of the ali- 

 mentary canal. From the two oviducts origi- 

 nate the proper ovarial tubes. In Athalia cen- 

 tifoli(E there are eighteen (a, b, c) attached to 

 each oviduct, but in some other instances, as 

 in Meloe, in which the upper part of the 

 oviduct on each side is dilated into an im- 

 mense bag resembling an uterus, they amount 

 to some hundreds of exceedingly short tubes 

 containing each but one or two ova. In Melo- 

 lontha and Lucanus there are six on each side, 

 but in some instances, as in Lixus, as shewn 

 by Dufour,* there are only two on each side. 

 These ovarial tubes gradually decrease in si?e 

 from their base to their apex, and those from 

 each side are collected together at their apices, 

 and are said to terminate each in a dilated 

 coacal extremity, but we must confess we have 

 never yet traced this structure in any instance. 

 Miiller, as above stated, traced a connexion 

 between the extremities and the ovarial tubes 

 and the dorsal vessel in Phasma, and many 

 other insects, as we have also done in several 

 instances, but the nature of these connexions 

 is disputed. They certainly appeared to us 

 to be vascular, as supposed by Miiller, and 

 we have already stated the reasons that led us 

 to the same opinion. 



We shall enter on a consideration of the 

 function of the organs of generation when con- 

 sidering this subject in MYRIAPODA. 



In concluding this lengthened article we 

 have only further to remark that the tegumen- 

 tary appendages consist of hair, scales, and 

 spines. The first of these serves as a covering 

 for the bodies of many species, more particu- 

 larly the Hymenoptera, and is also foun4 

 under the limbs in many Coleoptera. The 

 scales are peculiar appendages and may be 

 considered, according to many, as simply flat- 

 tened hairs. They entirely cover the bodies of 

 many species, as for instance the Lepidoptera. 

 The curious forms and marking of these parts 

 are sometimes exceedingly beautiful ; but the 

 limits of our article will not allow of our en- 

 tering at present on the consideration of them. 

 The spines are found much on the wing .of Hy- 

 menoptera and are often mistaken for true hairs, 

 between which and spines, and also between 

 these and scales, there is a difference of origin, 



* Annales des Sciences Naturelles, torn. vi. 

 pi. 20. 



3 T 



