WONDERFUL METAMORPHOSES. 79 



While growth and reproduction are proceeding 

 in the coralline, the older parts of it die. The 

 polyps disappear, and the lower branches frequently 

 drop off, leaving the trunk in this part bare. Thus 

 budding and dying are simultaneous in different 

 parts of corallines. In the large species, the main 

 stem or midrib becomes lifeless, or the mere support 

 for the numerous lateral plumes or branchlets. 



Some of these polyps are said to be absorbed 

 in their cells, and after a while to reappear. This 

 fact has been observed to occur at nearly regular 

 intervals. Thus all the cells of a living group have 

 been found empty after a certain period, or with 

 only the remains of the wasted polyps, the whole 

 evidence of vitality being the continued vibration 

 of the fluid of the trunk. The polyp heads seem 

 to drop off like a deciduous flower, yet, after ten 

 days or more, they are reproduced. Harvey observes, 

 that after he had kept a Tubularia two days, the 

 heads began to look unhealthy, and on the third 

 they were thrown off, and lay at the bottom of the 

 vessel. After another three days, during which the 

 water was changed, the polyps were entirely renewed, 

 with no essential difference except the absence of 

 colour. The cold of winter is said to strip off some- 

 times the polyp flowers, which remain apparently 

 dead till spring, when the coralline is warmed 

 anew into life, and the flowers are once more 

 apparent. 



According to Van Beneden, some corallines, when 



