662 SUMMARY OF CURRENT RESEARCHES RELATING TO 



it into a shallow dish, and remove any undesirable objects, such as worms, 

 large Crustacea, or large fragments of weed, which may have been washed 

 out of the sieve. These would otherwise rot, and set up putrefaction in 

 the water before the aquarium is properly in going order. Once the 

 tank is well started, Nature can generally be trusted to keep the balance 

 of life and death pretty equal, for the presence of a certain proportion of 

 Monads and Infusoria in the water, due to and living on the decay of 

 organisms which have died, seems to be beneficial rather than otherwise 

 to the Foraminifera, serving them as food. If these Microzoa appear to 

 increase too rapidly, which can be seen with the Microscope, or tested 

 by the sense of smell, they can be checked or stopped by increasing the 

 oxygenation of the tank, which is effected by exposing it for a short 

 time to the direct influence of sunlight. 



The natural evaporation from the surface of the aquarium would 

 rapidly render the water too saline for life, and this must be remedied 

 by the addition of the necessary quantity of fresh-water as required. 

 The easiest method of preserving the water at its correct salinity is to 

 place a pair of glass specific gravity bulbs in the tank. These can be 

 obtained at a very moderate cost from the dealers in chemical apparatus. 

 They are obtainable in pairs, clear glass and blue glass. The blue bulb 

 sinks to the bottom in normal sea-water, gradually rising as the salinity 

 increases owing to evaporation. The clear glass bulb floats in normal 

 sea-water and sinks if the specific gravity is reduced by the introduction 

 of too much fresh-water. The bulbs require a certain amount of care 

 in their use, as the attachment of any organism to the clear bulb will 

 cause it to sink to the bottom, while the blue bulb often rises under the 

 buoyancy of a bubble of oxygen derived from the weed. It is well, 

 therefore, to examine the bulbs before adding fresh water at random, 

 and the latter must be introduced a few drops at a time and left for 

 some minutes to mix with that in the tank. 



When the muddy debris is added to the tank, for many hours, or 

 sometimes days afterwards, few, if any, signs of Foraminifera will be 

 seen. They are all buried under the thin semi-liquid mud. But they 

 will gradually emerge and make their way towards the glass, up which 

 they slowly crawl by means of their pseudopodia, which can be seen 

 surrounding them in an opalescent halo if the tank be examined by 

 oblique light. In the course of a few days the glass sides will be seen 

 to be thickly studded with the tiny shells, prominent among which, owing 

 to its comparatively large size and great abundance, will be the hand- 

 some Miliolid, Massilina secerns d'Orbigny. Any specially interesting 

 species may be removed by means of a pipette to a smaller tank for 

 observation. 



For the purpose of examination there is nothing finer than the 

 Greenhow-Smith model of tank Microscope, made by Zeiss. With it 

 specimens can be examined in the 'tank under a comparatively high 

 power. But the strong light of a Nernst lamp is required to do justice 

 to it, although with the lower powers good results can be obtained with 

 an ordinary Microscope lamp and bullseye condenser. The best results 

 are obtainable with direct light, as the thickness of the tank militates 

 against the use of transmitted light. 





