62 



LIFE. IN ITS LOWER FORMS. 



that is needful is to place in a vessel of sea- water a frend 

 of sea-weed studded with the zoophyte, and in a few hours 

 scores or hundreds will be seen, even with the naked eye, 

 playing and dancing about in the most amusing manner. 

 Fig. d represents the embryo, very highly magnified. 



In structure the tiny animal, which, though just bom 

 of a stationary zoophyte, is now swimming at will in a 

 sprightly manner through the free water, is evidently a 

 Medusa ; in all essential particulars beiDg the very coun- 

 terpart of one of those exquisitely delicate animals which 

 Professor Forbes has so beautifully described and portrayed 

 in his "Monograph of the British Naked-eyed Medusae." 

 It consists of an umbrella-shaped disk of translucent jelly, 

 the diameter of which is about soth of an inch. Four 

 vessels cross the disk at right angles, and from the centre of 

 union there springs a fleshy peduncle, with a sort of neck, 

 capable of many varied motions and many alterations of 

 form. The margin of the disk carries twenty-four slender 

 tentacles, exactly corresponding to those of the parent 

 Polype, and essentially to those of the Hydra, being studded 

 with warts, which analogy pronounces to be aggregations 

 of barb-bearing capsules, instruments for arresting and 

 killing prey. At the bases of the tentacles, arranged at 

 certain definite points on the margin of the disk, are placed 

 eight beautiful organs, which are doubtless the seats of a 

 special sense. Each of these organs consists of a trans- 

 parent globe, not enveloped in the substance of the disk, 

 but so free as to appear barely in contact with it. In its 

 interior is borne a smaller globule or lens, of high refrac- 

 tive power, placed a little towards the outer side. Almost 

 every one, on first beholding these organs, would unhesi- 



