1072 



THE NATURE BOOK 



enveloping sheath and the cups which 

 give them protection. But even so, the 

 Sea SluG^s, with their lack of nice dis- 



Photo^raph hy A. I- . Daiiiiccy. 

 5. A.XTEXXVLARIA ASTEXXIA. 



crimination, annex them — horny skeleton 

 and all. 



But our zooids are socialists, nor 

 do they stay to distinguish between 

 " mine " and " thine." The stem from 

 which the branches grow, with their 

 groups of pinnae, is hollow, and so is the 

 base of each cup. And through these 

 channels the food caught and pre- 

 pared by any individual zooid is dis- 

 tributed to the whole colony. And this 

 is not more generous than necessary. 

 So low down in the scale of communal 

 life we find specialisation of function, 

 and that there are some members which 

 are incapable of obtaining food for them- 

 selves. But they must be fed — for, like 

 that of the queen bee, their duty is the 



highest — to produce the eggs from which 

 fresh colonies will be formed. One of 

 these reproductive members, lettered a, 

 is shown in the accompanying drawing 

 (see page 1071) of a considerabty magni- 

 fied portion of the colony represented 

 on page 776. 



The eggs are carried away by the tides 

 and soon hatch out into little larvae. 

 These are at first covered with minute 

 hairs, or cilia, by rapidly vibrating which 

 the larvae swim and reach a fa\-ourable 

 spot for settling down. \\"hen they have 

 done this they lose their cilia and form 

 the beginning of a fresh colony. 



Two specimens of Antevnularia antennia, 

 in some places popularly called Lobster's 

 Horn Coralline, are shown in illustrations 

 4 and 5. The first shows a dried colony 

 as generally found on the beach, with all 

 the pinnae rubbed off. In the second the 

 colony was in an aquarium when photo- 

 graphed. Illustration No. 6 is of a Sea 

 Oak Coralline {Sertiilaria pnmila), a kind 

 often to be picked up between the tide 

 marks on the blades of large weeds, and 

 specially interesting because of the phos- 



6. SEA OAK CORALLINE. 



phorescence of the edges of the zooid-cups. 

 You need only wait till the evening, 

 and then rap sharply the spray of sea- 

 weed on which your colony is growing, 

 and you will have an evanescent fairy 

 scene — the shining of a series of very tiny 

 glow-lamps. 



S. F. Maurice Dauncey. 



