130 



APPENDAGES TO THE MICROSCOPE. 



sorium, "which we have just detected in a drop of liquid under 

 examination upon an ordinary slip of glass (and covered with thin 

 glass), — we transfer this slip to the ' growing-slide,' fill the cup 

 with distilled water mixed with a small proportion of the water in 

 which the organism was found, and then so arrange the threads 

 (previously moistened with distilled water) that they shall pass 

 from the cup to the edge of the liquid in which the object is con- 

 tained. Thus, as the water evaporates from beneath the thin 

 glass, the threads will afford a continuous supply ; and the threads 

 will not become dry until the whole of the liquid has been ab- 

 sorbed by them and has been dissipated by evaporation. Fresh 

 supplies should of course be introduced into the cup from time to 

 time, as may be needed, so as to prevent any loss of liquid from 

 beneath the thin glass; and in this manner the most important 

 requisite for the continued growth of aquatic organisms, — a con- 

 stant supply of liquid, without an exclusion of air, — may be 

 secured.* 



97. Aquatic Box or Animalcule Cage. — This, also, is an ap- 

 pendage with which every Microscope should be provided, so 

 varied and so constant is its utility. It consists of a short piece 

 of wide brass tube, fixed perpendicularly at one end into a flat 

 plate of brass (Fig. 78), which is itself perforated by an aperture 

 equal in diameter to that of the tube, and having its opposite ex- 

 tremity closed by a disk of glass (b, b) ; over this fits a cover, 



formed of a piece 

 of tube just large 

 enough to slide 

 rather stiffly upon 

 that which forms 

 the box, closed at 

 the top by another 

 disk of glass (b, a). 

 The cover being 

 taken off, a drop of 

 the liquid to be ex- 

 amined, or any thin 

 object which can be 

 most advantageously 

 looked at in fluid, 

 is placed upon the 

 lower plate ; the 

 cover is then slipped 

 over it, and is 



Aquatic Box or Animalcule Cage, as seen in P ressecl do ^ n un *5 

 perspective at a, and in section at b. the drop of liquid 



* For descriptions of other forms of Growing Slide, see " Transact, of 

 Micros. Soc." Vol. xiv. p. 34, and " Quart. Journ. of Micros. Science," 

 N.S. Vol. vii. p. 11. 



Fig. 78. 

 A 



