TAGGART] CRAYFISH STUDY 105 



and a gravelly bottom, a plentiful number of crayfish may be 

 found under the larger stones. The simplest way to collect them 

 in this kind of a location is to stir up the stones with the net 

 handle or boots, and as soon as the water has cleared any number 

 will be crawling about. If the water is turbid from rains or melt- 

 ing snow, as it is apt to be in the spring, when the brook species 

 are laying eggs, and the females, with the attached eggs, are 

 wanted for class work, a great many may be gathered with the 

 aid of a net held across the stream against the bottom, then dis- 

 turbing them by overturning rocks and stones a short distance up- 

 stream. Thev are very sluggish and easy to collect in cold 

 weather. 



As to the aquarium itself, Professor E. A. Andrews, of Johns 

 Hopkins University, has a most interesting article in the Nature- 

 Study Review for December, 1906, on "Keeping and Rearing of 

 Crayfish for Class Use,'' which contains much valuable informa- 

 tion. Crayfish will live for months in ordinary glass aquarium 

 jars, either with or without aquatic plants, although the plants 

 are of advantage in keeping the crayfish in good condition. A 

 convenient aquarium may be made by fastening a piece of cheese 

 cloth over the top of a glass fruit jar into which water to the 

 depth of perhaps two inches has been poured, and then leaning the 

 jar against a support of some kind, tipping it just enough so that 

 the water will not run out. Two or three crayfish, if they are 

 at all large, are sufficient for one jar. The reason for tipping the 

 jar is to enable the crayfish to reach the air if the oxygen supply 

 of the water becomes exhausted or the water becomes foul. The 

 untimely death of those crayfish whose jars are filled with water 

 by the thoughtful small boy who feels that if he were crayfish 

 he would like lots of water, will probably occur several times. 

 Experience, however, although a little severe on the crayfish, 

 will probably soon teach that a very few inches of water are 

 sufficient — just enough to cover them and not so much that they 

 cannot expose their gills to the air. 



Temperature and light are two other important factors in 

 the keeping of crayfish. They should not be kept warm, as they 

 are much more active and require more food and oxygen and 

 the mortality is much greater. In winter time, placing the 

 aquarium before a window raised a few inches is usually suffi- 

 cient. A thin coating of ice on the water some cold morning 

 will not hurt them, although not many survive being in water 

 that has been frozen solid. Care must be taken not to expose 



