ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



139 



but should that be found necessary it is easily done by lifting the 

 cover carefully by means of the projecting horns on the top edge and 

 adding fresh water with a dipping tube. The apparatus is intended 

 more particularly for use as a shallow cell, so that moderately high 

 powers can be applied, yet the depth can readily be increased by 

 means of an intermediate plate the same size as the cover and with a 

 corresponding aperture ; this plate may either be of metal or ebonite, 

 and with this inserted between the lower plate and the cover the cell 

 is as free from leakage as before. 



The area of the cell is purposely rather large, as being more con- 

 venient for zoophytes, &c., but should it be desired to restrict the 

 movements of a lively object, it is only necessary to select a glass 

 ring rather thinner than the depth of the cell, place it in the middle, 

 fill the whole cell with water and place the object within the ring and 

 cover as before. 



Hardy's Examining Tank for Pond-Life, &c. — Mr. J. D. Hardy 

 exhibited at the last Conversazione a very convenient tank for showing 

 aquatic organisms. 



A A (fig. 27) are two uprights, each having a slot in which the 



Fig. 27. 



holders B B can be raised or lowered. The screw nuts C C keep the 

 holders in place, at the same time allowing the tank to be inclined at 

 any angle. The holders are not fastened to the tank, but clamp it so 

 as to leave it free to be moved through them, for the purpose of 

 bringing the tank more forward for examination with the Microscope 

 or otherwise. A piece of cork cut to fit loosely and float on the 

 water stops the water running out when the tank is tilted. 



The stand is weighted with lead at the bottom, and the tank, 



