60 NEW YORK AQUARIUM NATURE SERIES 



Probably the best method for securing the highest percent- 

 age of young is that of placing a cheesecloth net in the aquarium. 

 This should be partially filled with water plants and a breeding 

 female with one or more males placed in it as the time for egg- 

 laying approaches. After the process is complete, the fishes may 

 be replaced in the body of the tank, the plants removed to an- 

 other jar or breeding pan, and, if any eggs have adhered to the 

 net, as is usually the case, it also may be placed in the breeding 

 pan. 



When the young emerge, they will, of course, need to be fed. 

 The natural food of the young goldfish consists of minute Crus- 

 tacea and other tiny water animals and these may be reared in 

 cultures ready for their use. If this is not possible, they may be 

 fed on the yolks of hard-boiled eggs, finely rubbed up, and they 

 will thrive well on this diet. As they get a little older fine por- 

 tions of prepared fish food may be added. Boiled oatmeal and 

 other cereals strained through a fine sieve or coarse cloth are also 

 recommended. Care must naturally be taken not to overfeed to 

 the extent that the water becomes contaminated. 



THE USES OF LENSES. 



The observation of the smaller life of the aquarium is ren- 

 dered easier and much more attractive by the use of lenses. For 

 the study of the very minute forms nothing will suffice, of course, 

 except the compound microscope. For those which are some- 

 what larger and yet too small to be well observed by the naked 

 eye, the simpler hand lens will be satisfactory. Even a large- 

 sized reading glass, magnifying only two or three diameters, is 

 very useful, and may be arranged to stand permanently before 

 the aquarium jar. A cabinet, which has been in use at the New 

 York Aquarium for some years, is arranged so as to cut out the 

 view of everything except what can be seen through the lens and 

 it is lighted by incandescent lights placed behind the aquarium 

 jars. A reading-glass is easily arranged in a light frame of wood 

 placed in front of an aquarium lighted from a window. By this 

 means the exhibition of aquatic insects and larvae, the smaller 

 crustaceans, hydroids, sea-anemones, sea-mosses, etc., may be 

 made very attractive with little expense. 



For the study of very young fish, mosquito larvae, small 

 crustaceans, etc., it is advisable to have lenses of higher magnify- 

 ing power. Those magnifying six or eight times are perhaps 



