264 CLASS VIII. 
where a sinzle impregnation suffices for many families in succes- 
sion; the males are not observed until the end of summer or in 
autumn; they impregnate the last family, consisting of wingless 
females, which without copulation would be barren. Their eggs 
remain during the winter on branches of trees, and in spring 
produce only female plant-lice which without copulation are prolific 
and viviparous. Bonnet, to whom we owe this discovery, found 
that in the space of three months nine successive generations were 
produced without copulation}. 
Amongst the Myriapoda the Chilopods have only a single ovary, 
in form of a long sac situated beneath the intestine. In the 
remaining Insects there are two ovaries. Sometimes they have the 
‘same form of tubes or sacs (Forficula, Ephemera, Stratiomys); im 
some flies the sac is very long, rolled spirally like a watch-spring, 
and separated by many transverse partitions into cells. In most 
Insects each ovary consists of a number of tubes (gaines ovigéres — 
Leon Durour). Sometimes these are situated around a sacciform 
dilatation from which the oviduct arises (ovaria baccata), as in 
Meloé L. and Lycus (coleoptera)?. Or these tubes are situated 
lengthwise along the origin of oviduct (ovarta ramosa), as- in 
Cicada‘; sometimes on one side only, like the teeth of a comb, as 
in Phasma and Tenthredo (Athalia). But in by far the greatest 
number of cases, these tubes are situated at the beginning of the 
oviduct like the leaflets of a digitated leaf, at the end of a common 
stalk (ovaria digitata, fasciculata). Such ovaries are seen in the 
Lepidoptera, where each of them consists of four tubes. The 
number of these tubes is however very different, not only in the 
different orders, but even in the same order, and occasionally in the 
same natural family; whilst, ex. gr. Bombyx and Xylocopa (Hymen- 
optera) have four, in the Honey-Bee are more than one hundred*. In 
1 C. Bonnet, Traité d’Insectologie, 1. Observations sur les Pucerons, Paris, 1845, 
12mo. @uvres I. 1771, 8vo. Duvau has obtained even eleven successive generations 
without copulation; Ann. des Sc. nat. Vv. 1825, p. 224. There are also some examples 
of the same phenomenon in insects of other orders. BURMEISTER, 1. 1. s. 336, 337. 
2 Reaumur, Mém. pour servir a Hist. des Ins, iv. Pl. 29, f. 7 and 8. 
3 Branpt and RatzeBure, Medizin. Zoologie 11. Tab. xvii. fig. 2 k, Meloe varie- 
gatus, Tab. XIX. figs. 11, 15, Lytta vesicatoria ; LEON Durour, Ann. des. Sc. nat. VI. 
Pl. 18, fig. 1, Lycus rufipennis. 
4 Léon Durour, Hémiptéres, Pl. 17, fig. 189. 
° Lton Durour, Mém. présentés, Tom. vit. p. 408. According to SWAMMERDAM, 
