72 HOUSE, GARDEN, AND FIELD 



tures which move slowly by the gentle contraction of 

 glassy bells, others which travel slowly through the water 

 without any means of propulsion that the naked eye or a 

 hand-lens can reveal. Again we are warned not to run 

 the risk of distraction. Even to name all the living objects 

 that the eye can recognise in one of these beakers would 

 be a waste, not so much of time, for time is cheap on an 

 idle afternoon, but of attention, which is soon exhausted 



FIG. 16. Nauplius of rock- barnacle, magnified. 



and not easily repaired. We will remark one thing only, 

 and I have my reasons for choosing these little white 

 specks, just visible to the naked eye, which make short 

 jerky leaps in rapid succession. With a dipping- tube it is 

 easy to pick up a few, and transfer them to a watch-glass 

 set on a strip of black paper. Then a good pocket-lens 

 will show us what they are. We can make out an oval 

 body, narrowing behind to a point, and three rather long 

 pairs of limbs fringed with bristles. A microscope is 

 needed to make out the details shown in the accompany- 



