130 PRACTICAL TREATISE ON THE MICROSCOPE. 



in the hand, or similarly attached to the opposite side of 

 the same plate, but provided with cutting edges like the pair 

 of scissors said to have been invented by Swammerdam, are 

 employed together; the former of these retains the subject 

 firmly whilst it is being cut by the latter. These forceps will 

 be again alluded to in the chapter devoted to dissecting in- 

 struments. 



Animalcule Cages. — Instruments known by the name of 

 " live boxes " have been in use for many years, and all the old 

 microscopes were furnished with them ; they consisted of a brass 

 cell, from three-quarters to one inch-and-a-quarter in diameter, 

 into which a planoconcave glass was made to drop ; upon the 

 concave side the insect was placed for examination, and a flat 

 piece of glass of the same size, but fastened into the bottom of 

 another cell, could be screwed down upon the insect, so as to 

 prevent its movement ; this instrument has now been entirely 

 superseded by more convenient forms, and amongst them may 

 be mentioned the animalcule cage of Mr. Tulley, and the 

 capillary tablets of Mr. Varley. The animalcule cage sup- 

 plied with the compound achromatic microscope of the late 

 Mr. Tulley is represented by fig. 81 ; it consists of a plate 



of brass, from three to four 

 inches in length, to the middle 

 of this was attached a piece of 

 brass tube, about three-quarters 

 of an inch in diameter, into the 

 Fig. 81. top of which was fastened a plate 



of thick glass ; over this tube an- 

 other short one, having a cover of thin glass cemented to a 

 rim at its top, is made to slide ; this last tube is sufficiently 

 short to allow the thin glass cover and the plate in the fixed 

 tube to be brought into contact. The drop of water contain- 

 ing the animalcules to be examined, is put upon the piece of 

 plate-glass, which may be termed the object-plate, and the 

 tube containing the thin glass cover is then to be slid down 

 carefully, so that the drop may be flattened out ; in order to 

 allow the contained air to escape in the sliding down of the 

 cover, a small hole is drilled in the top ; this may be subse- 



