AQUARIA IN SUMMER. 369 



The instrument mentioned is composed of a gutta 

 percha globe, made in the manner previously de- 

 scribed, into one end of which is inserted a tube of 

 gutta percha or glass about four inches long, and 

 at the opposite end of the ball is introduced a second 

 tube about eight inches in length. 



To use this instrument, close the orifice of the 

 longest tube, and plunge it into the water over any 

 spot where the debris is collected, then by removing 

 your finger from the end of the tube, the impurity 

 will be instantly sucked up into the ball. By again 

 placing the finger in its former position, the siphon 

 may be lifted out of the tank, and its contents 

 allowed to run off into a jug or basin placed near for 

 the purpose. 



This operation must be repeated until the whole 

 of the offending particles are removed. Of course, 

 more water will be drawn off than is necessary, but 

 it can easily be poured back into the tank as soon 

 as the sediment has been fully precipitated. 



Aquaria are generally much more difficult to keep 

 in order in summer than in winter, owing to the 

 rapid and profuse growth of minute vegetation which 

 renders the water opaque and exceedingly unpleasant 

 to the eye. 



This ugly opacity I at one time attributed to de- 

 caying animal matter, for I could scarcely believe 

 that the mere increase of the algze spores could pro- 

 duce such a vile effect. Experience, however, has 



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