The elements of insect anatomy The elements of insect anatomy : an outline for the use of students in entomological laboratories elementsofinsect00comst Year: 1916 87 when the more primitive or generalized members of different orders are compared with each other. In most of the orders of insects the greater number of species have become so modified or specialized as regards the structure of their wings that it is difificult at first to trace out the primitive type. Note.—The student should have a clear idea of the significance of the terms generalized and specialized, which are now much used
The elements of insect anatomy The elements of insect anatomy : an outline for the use of students in entomological laboratories elementsofinsect00comst Year: 1916 87 when the more primitive or generalized members of different orders are compared with each other. In most of the orders of insects the greater number of species have become so modified or specialized as regards the structure of their wings that it is difificult at first to trace out the primitive type. Note.—The student should have a clear idea of the significance of the terms generalized and specialized, which are now much used in biology. Generalized indicates a primitive condition, a nearness to ancestral forms. Thus, the most generalized member of a group (as a family or an order) is that member which most clearly resembles the ancient progenitor of that group. Specialized, on the other hand, indicates remoteness from the primitive type, an adaptation to more special conditions of existence. Thus, the most specialized member of a group is the one that departs most widely from the ancient progenitor of that group. Thpse terms are used in a comparative sense ; thus, a highly specialized form may be regarded as generalized when compared with forms that are still more highly specialized. The specimens indicated for the student to study in the following part of this course have been selected with care to illustrate gradually increasing degrees of divergence from (he primitive type. In the case of each order studied, the work begins with a comparatively generalized form, and passes step by step to those that are more specialized. The flies of the genus Rhyphus afford good examples of comparatively generalized wings. By studying a wing of one of these flies and the accompanying figure (Fig. 2) the
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