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The world-wide damage caused by the larvae of various lamellicorn beetles to sugar-cane, cassava, pasture land, root crops, and miscellaneous economic trees and plants, has engaged the undivided attention of many scientists during the last thirty years or more. The "White Grub" question in America, the notorious Cockchafer or "May Bug" in Europe, and the formidable "Grub Pest" of Australian cane-fields, constitute exceedingly complex problems which have for many years defied the efforts of entomologists, and at the present time, although partially solved, cock chafer beetles still continue to be responsible for tremendous financial losses. I t is interesting to note that the destructive species in each of these three examples are classed amongst the Melolonthinae, most of the grubs of which subfamily, in addition to their habit of ingesting soil and extracting from it organic matter, also devour living roots and the growing vegetable tissue of harder underground portions of plants. While theĀ· majority of Queensland cane-beetles (including our most destructive) belong to the M elolonthinae; the subfamily Rutelinae. is also represented in our cane-fields by two species, both of which, however, happen to be of minor importance. In the present article it is my intention to deal with six of our northern scarabaeid beetles, all of which are common at times under cane-stools, and inflict damage of a more or less serious nature to the setts, roots, and subterranean basal portions of growing cane-sticks.
Material of the domestic fowl of appropriate ages, ranging from twelve hours' incubation to the adult bird, was prepared for the purpose of studying the production and development of the germ cells. The primordial germ cells arise in the extra-embryonic region anterior to the head fold in the region of the zone of junction during the primitive-streak stage. These germ cells migrate, through the blood stream, to the region of the future gonad, where they develop into the definitive germ plasm. There is no widespread degeneration of the primordial germ cells after their arrival in the gonadal region, nor is there any widespread transformation of somatic cells into definitive germ cells.