64 collector's manual- 



water. Either sea water or fresh water may be used for mixing. 

 Formalin, unlike alcohol, does not need to be brought up to 

 strength subsequently. At all times crowding of specimens in 

 containers should be avoided; see also the remarks under alcohol 

 with respect to brittleness and killing. When killing animals with 

 formalin a little of the prepared solution should be added from 

 time to time to the water in which the animals are killed. After 

 killing, the specimens should be transferred to a fresh solution of 

 formalin. 



Soft-bodied animals such as worms are preferably killed in 

 an expanded condition. A very gradual addition of alcohol to 

 fresh water, or formalin to either fresh or salt water, will serve 

 to put them to sleep if no other narcotizing agents are at hand. 

 For marine animals one of the best and most easily obtained 

 narcotizing agents is magnesium sulphate, to be used in the 

 proportion of 154 grams to the liter of water (5.5 oz. to 2.1 pints). 

 The animals may be placed directly in this solution at sea 

 temperature or preferably cooler. When insensitive to being 

 touched, they can be transferred first to weak alcohol or 

 formalin for killing, and then to the strong solution for permanent 

 preservation. In the Tropics narcotizing must not be too pro- 

 longed, as unless the process is carried out in a refrigerator, the 

 animals will macerate because of the high temperature. 



Containers, if not otherwise provided, can usually be obtained 

 from the camp or ship's cook. Pickle, preserve, and mayonnaise 

 jars with screw caps are good. In place of gaskets, waxed paper 

 over the mouth of the bottle under the lid is usually satisfactory, 

 if not broken when the lid is screwed down tight. Tin cans with 

 spring tops are excellent containers. Tin cans with slip-over 



