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MANIPULATION. 



some part or other of its existence. The subjoined list could 

 be carried on almost ad infinitum, but it has been deemed 

 necessary only to include in it such specimens as exhibit some 

 interesting points of structure. Those who would wish to see 

 figures and descriptions of a great number of species, should 

 consult the Anoplurorum of Mr. Denny, a work devoted 

 especially to the subject.* Some of the parasites are claimed 

 by the entomologist as belonging to the class Insecta, which 

 includes all that have six legs, whilst others, having eight, 

 and commonly called Acari, are included in another class 

 termed Arachnida. In the present case such a distinction is 

 not necessary ; they wUl, therefore, all be termed Parasites 

 or Epizoa, and the animals from which they are taken placed 

 in alphabetical order: — 



Some very minute insects, termed Aphides, are abundant 

 on most plants, the leaves of which they speedily injure and 

 destroy; others again, to which the term Cynips has been 

 assigned, are the cause of certain excrescences on the leaves 

 of plants and trees termed galls. The well-known oak-apple 

 is produced by an insect termed the Cynips quercus, a most 

 exquisite object when examined by reflected light ; the same 

 also may be said of the insect from the gall of the rose. In 

 order to collect the Cynips from these structures, they should 

 be gathered when ripe, and placed in a box covered with 

 * Monographia Anoplurorum Britannia, by H. Denny. London, 1842. 



