356 EVENINGS AT THE MICROSCOPE 



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 resem- 

 blance. 



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 

 vigor 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-colored 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 ap- 

 preciating 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 colored 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 of 

 a quarter of an inch long; then lengthened again to an 



