METRIDIUM. 



11 



tacles, at first only few in number, are in fact so many extensions 



of the inner chambers, gradually narrowing upward till they 



form these delicate hollow feelers which make a soft downy fringe 



all around the mouth. (Fig. 7.) They do not start abruptly from 



the summit, but the upper margin Fig . 7 . 



of the body itself thins out to a ,,^,,,0^ 



form more or less extensive lobes, 



through which the partitions and 



chambers continue their course, 



and along the edge of which the 



tentacles arise. 



The eggs are not always laid in 

 the condition of the simple planula 

 described above. They may, on the 

 contrary, be dropped from the par- 

 ent in different stages of develop- 

 ment, sometimes even after the tentacles have begun to form, as 

 in Figs. 8, 9. Neither is it by means of eggs alone that these 



Fig. 8. 



Fig. 9. 



animals reproduce themselves ; they may also multiply by a pro- 

 cess of self-division. The disk of an Actinia may contract along 

 its centre till the circular outline is changed to that of a figure 8, 

 this constriction deepening gradually till the two halves of the 8 

 separate, and we have an Actinia with two mouths, each sur- 

 rounded by an independent set of tentacles. Presently this sepa- 

 ration descends vertically till the body is finally divided from 



Fig. 7. View from above of an Actinia with all its tentacles expanded ; o mouth, b crescent-shaped 

 folds at extremity of mouth, a a folds round mouth, 1 1 1 tentacles. 

 Figs. 8, 9. Young Actiuiie in different stages of growth. 



