CLASSIFICATION OF ANIMAL PREPARATIONS. 425 



the same interesting class of animals, that will amply repay a 

 careful examination and dissection : — 



Ovipositor of Cicada, Web of Clubiona atrox, 



Cynips quercus, Jaw of Locust, 



Drone-fly, House-cricket, 



Field-cricket, Mantis, 



Ichneumon, Drum of Cicada, 



Saw-fly, File of Cricket, 



Spinneret of Spider, Grasshopper. 



PREPARATIONS FROM THE HIGHER ANIMALS. 



Blood.* — To examine this vital fluid, it is necessary to place 

 upon a glass slide a small drop recently taken from the 

 animal ; a cover of mica, or of the thinnest glass, should be 

 laid over the drop, which is then ready to be viewed with the 

 highest powers. If it be required to reserve a specimen for 

 future examination, a very small quantity should be spread in 

 the thinnest possible layer upon a glass slide, which is then 

 to be passed rapidly backwards and forwards through the air, 

 so as to dry the blood as quickly as possible, when the discs 

 or corpuscles will be found to have altered but little in shape ; 

 in order to prevent the preparation from being injured, or 

 even rubbed off, a cover of the finest glass should be laid over 

 it, and cemented down in the manner described at page 313 ; 

 a specimen so mounted may be kept for years. The following 

 vertebrate animals will exhibit the most marked peculiarities, 

 the corpuscles being largest in reptiles and fishes, and smallest 

 in birds and mammals : — 



* Those who may wish to learn the comparative sizes of the blood 

 corpuscles in the vertebrate animals, should consult the valuable table of 

 Mr. Gulliver, published in the clii. number of the Proceedings of the 

 Zoological Society. 



