ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



671 



obtained, which is an advantage when higher powers than the one- 

 inch are employed. 



For keeping the glass apart, the " extra thick " indiarubber bands 

 are the most generally useful, and in putting the trough together care 

 must be taken to have the indiarubber and glass perfectly dry, as 

 otherwise there is danger of a capillary leak. 



Hardy's Vivarium.* — Mr. J. D. Hardy suggests a trough (or 

 vivarium as he prefers to call it) which obviates the main objections 

 to the old troughs, viz. : — (1) Their superfluous depth ; (2) The 

 necessity for taking out the object and bottling it if desired to carry 

 it anywhere for exhibition ; (3) The water in the trough (through its 

 being open at the top) is always more or less susceptible to every 

 movement, causing some objects to have a constantly oscillating 

 motion ; (4) Their non-reversibility ; and (5) The necessity for 

 keeping them upright. 



The apparatus (Fig. 153) consists of two pieces of glass 3 in. x 2 in. 

 or 2 inches square, to the lower of which is cemented an india- 



FiG. 153. 



'r ^ fe ^ 



rubber or glass ring of any desired thickness, and this is covered on 

 the upper side with some adhesive substance or simply greased to 

 render it impervious. A funnel-shaped piece about J inch wide is 

 cut out of the ring at the top and the upper plate put on the ring, and 

 the whole held together by strong indiarubber rings or springs. 



The object having been placed on the lower plate, the upper one 

 is put on, and the cell filled up with water through the hole at 

 the top. The apparatus is reversible, and it can be plunged into a 

 beaker of water in any position without fear of losing the object. 



In view of the difficulty of using thin glass for high powers which 

 would not bear the pressure required to keep the cell water-tight, 

 Mr. Ingpen suggests f the use of two semicircular clips so as to be 

 exactly over the indiarubber ring. 



Simple Growing-slide.t — Mr. T. Charters White suggests a form 

 of growing-slide which contains its own fluid, and may be left under 



* Jouru. Quek. Micr. Club, vi. (1881) pp. 212-3 (1 fig.), 

 t Ibid., pp. 221-5. X Ibid., pp. 201-2. 



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