314 EVENINGS AT THE MICROSCOPE. 



Ha ! but you don't want to be caught, eh ? 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 Medusa, as eyes, 

 rudimentary organs of vision, capable, probably, of appre- 

 ciating the presence and the stimulus of light, without the 

 power of forming any visual image of external 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 mere fragments a 

 quarter of an inch long ; then lengthened again to an 

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



