. The Cambridge natural history. Zoology. 586 HEMIPTERA-HOMOPTERA known as parallel series. This has been recently investigated in the genus Ghermes hj Blochmann, Dreyfus, and Cholodkovskj'. This latter savant informs us ^ that a wingless parthenogenetic female of Chcrmes hibernates on a fir-tree—Picea exceha—and in the spring lays numerous eggs; these hatch, and Ijy the effects of suction of the Chermes on the young shoots, galls are formed (Fig. 286), in which the Insects are found in large numbers; when they have grown the galls open, and allow- ing the Insects to escape these moult and bec
. The Cambridge natural history. Zoology. 586 HEMIPTERA-HOMOPTERA known as parallel series. This has been recently investigated in the genus Ghermes hj Blochmann, Dreyfus, and Cholodkovskj'. This latter savant informs us ^ that a wingless parthenogenetic female of Chcrmes hibernates on a fir-tree—Picea exceha—and in the spring lays numerous eggs; these hatch, and Ijy the effects of suction of the Chermes on the young shoots, galls are formed (Fig. 286), in which the Insects are found in large numbers; when they have grown the galls open, and allow- ing the Insects to escape these moult and become winged females. They now take on different habits; some of them remain on the Picea, lay their eggs thereon, and out of these there are produced young that grow into hibernating females, which next spring produce galls as their grandmothers did; but another portion migrates to the Larch {Larix); here eggs are laid, from which proceed wingless partheno- genetic females, that hibernate on their new or secondary plant, and in the following spring lay their eggs and give rise to a dimorphic generation, part of them becoming nymphs and going on to the winged condition, while the other part remain wingless and lay eggs, that give rise to yet another wingless generation ; in fact, a second pair of parallel series is formed on the new plant, of which one is wingless, and exclusively parthenogenetic, and continues to live in this fashion for an indefinite period on the secondary plant, while the other part becomes winged; these latter are called sexuparous, and go back to the Picea, and there lay eggs, that give rise to the sexual forms. If we would summarise these facts with a view to remembering them, we may say that a migration of a part of a generation from the Picea was made with a view of producing a sexual generation, but that only a portion of the migrants suc*^ ceeded in effecting the object of the migration, and this only in generation. Tlius portions remained on the P
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
