sustained by its fellow polypites, as well as having a certain amount 

 of individuality, and all work for the general good of the colony. 



Each polypite inhabits a separate cell or calycle, into which it 

 retreats when alarmed. When confidence is restored it projects its 

 tentacles, spreads them out, and by means of ciliary action attracts 

 its food, which is drawn into the mouth situated in the centre of the 

 whorl of tentacles. 



The ccenosarc (the continuation of the body) is tubular, therefore 

 the food captured by each individual polypite affords nourishment to 

 the whole colony. . 



At certain portions of the polypary are seen much larger cells — 

 the gonotheca or capsules — in which are developed the reproductive 

 organs (the gonophores). They vary much in shape, and so help in 

 determining the different species. In some species both male and 

 female organs are developed on the same individual. 



The sexual Zooids may be either fixed or free. Sometimes they 

 discharge their contents in situ, at others they leave the parent 

 colony and enter upon an independent existence. They afford a 

 complete contrast to the parent, being shaped like a medusa, of a 

 crystalline umbrella form, which has the power of contraction and 

 expansion, enabling it to swim freely in the water. 



From the centre of the crystal bell is suspended a hollow organ 

 called the manubrium, which terminates in a mouth. Around the 

 margin of the bell are seen numerous tentacles, and also a collection 

 of pigment cells, each containing a crystalline body. These are 

 supposed to be rudimentary eyes. 



It is curious that it is only on Zooids destined to be free that 

 these eye-spots are developed. 



The generative organs are developed inside the bell, in the walls of 

 the manubrium, sometimes before detachment, at others long after 

 the Zooid is liberated from the colony. 



After a time the little medusa loses its activity, and reverses its 

 umbrella, which shrinks up into a shapeless mass, causing the pro- 

 jection of the manubrium ; the contained ova are then liberated. 



As to the appearance of these lovely little forms I cannot do 

 better than quote from Hincks' " British Hydroid Zoophytes." He 

 says : "It would be difficult to exaggerate in speaking of the beauty of 

 these floating flower-buds, as they may well be called. The vivid 

 tints which they often display, the gracefulness, of their form, the 

 exquisite delicacy of their tissues, and the vivacity of their movements, 

 combine to render them singularly attractive. Frequently they are 

 so perfectly translucent that their bubble-like forms only become 

 visible in a strong light. In other cases the umbrella is delicately 

 tinted, while the manubrium displays the gayest colouring, and 

 brilliant ocelli glitter on the bulbous base of the tentacles. To their 

 other charms that of phosphorescence is often added ; they are not 

 only painted like the flower, but at night they are jewelled with vivid 

 points of light, set round the margin of the bell, or one central lamp 



