136 A NURSERY FOR THE MICROSCOPE. 



would be the progenitor of four millions and a quarter 

 of young in twelve months, if undisturbed. Her 

 motherly devotion is seen in the way in which she 

 swims about with her purse-like egg-bags trailing 

 behind her. The young are ludicrous objects, with 

 nothing of the gracefulness of their parents. They 

 have a crab-like form, which indicates their crustacean 

 belongings, and they move about in the most cranky, 

 jerky manner it is possible to conceive, like the big 

 seconds finger of a large clock. 



Both Cyclops and water fleas (Daphnia) have such 

 a transparent skin that we can see their internal 

 organs, and watch them fulfilling their several func- 

 tions. As is the case in most insects, the female is 

 larger in size than the male. These creatures are 

 a very old race, for we find them fossilised in carbo- 

 niferous shales in such prodigious numbers that we 

 feel assured they must have bred as plentifully 

 millions of years ago as they do now, when they 

 not unfrequently darken the water of our ponds with 

 their countless crowds. During entire geological 

 periods they have been the food-stock of fresh-water 

 and marine fishes alike, and we find them adapted 

 to all conditions of aquatic life. 



Space forbids us to notice other common micro- 

 scopic objects which may be readily introduced into 

 the parlour tank, and kept ready for observation. 

 They might thus while away many an hour of gloom 

 and perchance of sickness or sorrow ; and cannot fail 

 to add another element of interest to aquarium keep- 



