Marine Aquaria 15 



ployed in the laboratory for some other purpose and may have been in 

 contact with such toxic substances as corrosive sublimate, picric acid, 

 salts of chromic acid, or formalin. There is a considerable difference 

 in the degree of absorption of poisons by glass, corrosive sublimate for 

 instance being the most difficult to remove. When chromium cleaning 

 fluid has been used glassware must be meticulously washed to remove 

 traces of chromium salts. Glassware available in marine laboratories 

 should always be regarded with a certain degree of suspicion because 

 of the impossibility of ascertaining the purposes for which it was pre- 

 viously employed. 



New glassware just delivered from the factory need not be washed 

 with cleaning fluid. It should be rinsed in water and, if necessary, 

 washed with "Bon Ami" which is preferable to soaps and soap powders 

 because it is more readily removed. After being used for keeping eggs 

 and larvae the dishes should never be washed directly in freshwater 

 because of the danger of the cytolyzed cells sticking to the glass (Just, 

 1928). They should be first rinsed with sea water and then washed with 

 freshwater. In drying the glassware, towels coming from the laundry 

 should be avoided because of the alkali present in them. If it is neces- 

 sary to wipe the glassware, cheesecloth or other soft material washed 

 free from chemicals should be used. Clean dishes should be stacked on 

 filter paper or a clean dry cloth and protected from dust. The practice 

 of placing them upside down on the laboratory table is undesirable be- 

 cause of the possibility of chance contamination. Glassware used in the 

 cultivation of diatoms and other algae should be sterilized in a dry oven 

 {1Y2 hours at i6o°C). 



The use of celluloid. Very often the investigator is confronted with 

 the necessity of making a tank or an apparatus of a special design to be 

 used for a physiological or embryological experiment. The problem is 

 easily solved by using celluloid which is made in sheets about 3x5 feet, 

 ranging in thickness from 0.005 to °- I2 5 i ncn - The celluloid manu- 

 factured by the Dupont Company and other companies producing 

 cellulose by-products may appear in the market under different trade 

 names (pyralin, viscoloid, etc.). Clear as well as opaque celluloids and 

 that frosted on one or both sides are available. The thin sheets are 

 almost as transparent as glass but the thicker ones are less clear and 

 have a slightly yellowish hue. Celluloid sheets may be cut by scissors or 

 sawed with a hacksaw. After the edges have been filed and sandpapered 

 the pieces may be stuck together with glue made of a thin solution of 

 celluloid in acetone. This solution dries very quickly and the making 

 of the apparatus presents no difficulty. 



Strips and sheets of celluloid may be bent to a desired shape by 

 warming them in hot water. After being cooled they become rigid again. 



