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Sea^Matcr Hquaria* 



By R. Lawton Roberts, M.D. 

 Illustrated by Miss Florence Phillips. 

 Plates V. and VI. . 



HE illustration (Plate V.) represents the general plan 

 of a small private aquarium, constructed on the 

 principles (i) that f/ie ivater is circulated^ but 7iot 

 changed ; and (2) that the only vegetation present is 

 such as developes from invisible germs existing in the 



"* 1^ In 1872, the late W. A. Lloyd wrote :—" The 



balance of existence between plants and animals in a 



streamless aquarium is never easy to maintain, and 



therefore amateurs have usually to choose between the meagreness 



of a tank with but very few and small animals in it, and one with 



so many that the destruction of the whole can be very quickly 



brought about by some small adverse circumstance ; and there 



frequently is no choice between an aquarium with the water 



looking dull from an insufficiency of oxygen caused by too little 



light to act on the vegetation, and one with an exposure to so 



much light that the plants evolve so many spores (or seeds) that 



the water becomes opaquely turbid and of a greenish-brown hue. 



A stream of water in an aquarium, however, with the greater part 



of the water in a separate vessel, the latter containing no animals 



and never being exposed to light, and with a smaller part of the 



water containing the animals, and being fairly well illuminated, at 



once surmounts many difficulties, and is (so to speak) a 'fly-wheel 



which carries the whole machine of an aquarium over its dead 



points. But such an arrangement is expensive, and needs much 



attention in vvorking it." 



It is precisely "such an arrangement" that I have attempted 



to carry out in a practical manner, and the result of my efforts is 



figured in the accompanying illustration (Plate V.). 



The tank (2) is strongly constructed, the base and ends being 



of slate, and the sides of plate glass ; its internal measurements 



International Journal of Microscopy and Natural Science. 

 Third Series. Vol. III. j 



