314 EVENINGS AT THE MICROSCOPE. 



Ha ! but you don't want to be caught, eh 1 And so you 

 pump and shoot round and round the jar as the spoon 

 approaches ! Truly you are a supple little subject, difficult 

 to catch as a flea, and difficult to hold (in a spoon) as an 

 eel. But here you are at last, lying as motionless and as 

 helpless in the silver as a half-melted atom of calf's-foot 

 jelly, to which, indeed, you possess no small resemblance. 



Look at the pretty little Medusa in his new abode, at 

 once recovering all his jelly-hood as he feels the water 

 laving him, and dashing about his new domain with a 

 vigour which makes up for lost time. 



It is a tall bell of glass a little contracted at the mouth 

 — its outline forming an ellipse, from which about a third 

 has been cut off. The margin of this bell carries four tiny 

 knobs, set at equal distances, and thus quartering the 

 periphery ; and these are the more conspicuous, because 

 each one is marked with a bright orange-coloured speck. 

 Physiologists are pretty well agreed to consider such 

 specks as these, on the margins of the smaller Medusce, 

 as eyes, — rudimentary organs of vision, capable, probably, 

 of appreciating the presence and the stimulus of light, 

 without the power of forming any visual image of ex- 

 ternal objects. You will not gain much information 

 about their function from microscopic examination ; for 

 all you can discern is an aggregation of coloured specks 

 (pigment-granules) in the midst of the common jelly. 



The knobs, however, are connected with other organs ; 

 for from each of them depends a highly sensitive and very 

 contractile tentacle. Sometimes one, or more, or all, of 

 these organs hang down in the water motionless, lengthen- 

 ing more and more, especially when the bell is still, until 

 they reach a length some twelve or fifteen times that of 

 the bell, or umbrella. Then suddenly one will be con- 

 tracted, and, as it were, shrivelled, to a mere fragment a 

 quarter of an inch long ; then lengthened again to an 

 inch or two; then shortened again. Now the little bell 



