1 6 Marine Invertebrates 



Celluloid is non-corrosive and apparently insoluble in seawater. It 

 has proved to be the most valuable and indispensable material for the 

 physiological work carried on in the author's laboratory at the U. S. 

 Bureau of Fisheries station at Woods Hole, Mass. (See note i on p. 50.) 



Seawater supply. Marine biological laboratories are usually pro- 

 vided with running seawater pumped from the sea and stored in tanks. 

 The installation of a satisfactory salt water system is primarily an 

 engineering and architectural problem the discussion of which is beyond 

 the scope of the present book. It suffices to mention here that seawater 

 delivered to the laboratory tables must be pure and should not con- 

 tain toxic substances. Attempts are always made therefore to avoid its 

 contact with heavy, easily oxidized metals such as iron and copper by 

 using lead, rubber, or rubber-lined steel pipes and nickel or rubber 

 pumps. Many marine laboratories use large capacity bronze pumps 

 which give satisfactory results, for the seawater comes in contact with 

 the metal part of a pump only for a very short time. Celluloid has been 

 recommended for pipe and fittings and is very successfully used by the 

 Biological Station and Aquarium at Helgoland (Hagmeier, 1925). Sea- 

 water delivered to a laboratory table through rubber-lined or celluloid 

 pipes seems to be deprived of toxic substances, and may safely be used 

 for physiological experiments and the cultivation of the most delicate 

 marine forms. 



The investigator is sometimes confronted with the necessity of con- 

 ducting his research in a locality remote from a permanent biological 

 station. He can, however, easily provide himself with running seawater 

 by purchasing a small centrifugal pump with an electric motor, a suf- 

 ficient length of ordinary garden hose and a small tank which should be 

 supported by a platform. A pump delivering 5-10 gallons a minute 

 and two 5o-gallon wooden barrels for a storage tank, placed 5-6 feet 

 above ground will provide a sufficient amount of running water for four 

 or five aquaria. One of the barrels may be equipped with a float con- 

 nected to a switch controlling the operation of the motor so that the 

 pump works only when the water in the barrels reaches a certain low 

 level. The whole equipment may be purchased and assembled for about 

 $60.00. 



It has been the author's experience in establishing small temporary 

 laboratories in various localities along the Atlantic and Gulf coasts that 

 ordinary cast iron pumps are preferable to bronze ones. There is but 

 little oxidation of iron when the pump is in operation and consequently 

 water delivered to the laboratory is not toxic. Furthermore, water sup- 

 plied under similar conditions by bronze pumps proves to be much more 

 harmful to a number of marine forms, such as lamellibranch larvae, that 

 are very sensitive to minute amounts of copper. 



