File:Guide to the study of insects and a treatise on those injurious and beneficial to crops, for the use of colleges, farm-schools, and agriculturists (1889) (14776610185).jpg

Identifier: guidetostudyofin00packar (find matches)
Title: Guide to the study of insects and a treatise on those injurious and beneficial to crops, for the use of colleges, farm-schools, and agriculturists
Year: 1889 (1880s)
Authors: Packard, A. S. (Alpheus Spring), 1839-1905
Subjects: Insects Beneficial insects Insect pests
Publisher: New York, H. Holt and Company Boston, Estes & Lauriat
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Smithsonian Libraries

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from the adult in having longer feet, and four instead often genital cups, the latter being the usual number in the adult.. The larvae are elongated oval, with six long legs and fourocelli. They swarm for a short time over the gills of the mus-sel they are living on and then bore into the substance ofthe gill to undergo their next transformation. Here the youngmite increases in size and becomes round. The tissues soften,those of the different organs not being so well marked as inthe first larval stage. The limbs are short and much larger * The development of spiders and of the Arachnids generally, has been tracedby Rathke, Herold, and more especially by Claparede, in a work of great ability,fi-om which we liave drawn the preceding account, often iising the authors ownwords. His observations Avere made on various genera of spiders (Pholcus, etc.)His Studies on Mites, from which Plate 11 is copied, appeared in Siebolds and.Kollikers Journal of Scientific Zoology, 1808, part iv. PLATE i;
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METAMORPHOSTS OF IVTITES. ARACHNIDA. 641 than before, the whole animal assuming an embryo-like appear-ance, and moving about like a rounded mass in its enclosure.Indeed is this process not (though Claparede does not say so)a histolysis of the former larval tissues, and the formation of anew body, as in the change of the six-footed insect beneath thelarva skin, where the pupa is formed ? A new set of limbsgrow out, this time there being four instead of three pairs oflegs, while the old larval skin is still embraced witliin themembrane containing the second larval rounded mass. 8oon:the body is perfected, and the pupa, as we may properly call it,slips out of the larval membrane. The second larva after some time undergoes another*change ; the limbs grow much shorter and are folded beneaththe body, the animal being immovable, while the wliole bodyassumes a broadly ovate form, and looks like an embryo justbefore hatching, but still lying within the egg. This may alsobe comparable with the

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