204 ZOOPHYTES. 



life of the product. Its regular decay commences in the subordinate parts, 

 at the point farthest from the principal part. When beginning at the 

 extremity, decay descends gradually from the newest, slenderest, and weak- 

 est parts towards the stronger and older. But its progress may be ar- 

 rested, and then vigorous regeneration ensues from the point of interrup- 

 tion. Next, the transparent vacant tubular portion above, which the pith 

 had occupied, drops off, and a new shoot rising from the stalk thus muti- 

 lated, is clothed in time, like its precursor, with twigs, bearing cells and 

 hydr£e. Intermediate interruptions of the pith from decay, throughout 

 the stem and branches, produce similar consequences. Besides these, 

 many sproutings vegetate from the lower parts of \igorous branches, where 

 none were previously seen. All this contributes to the luxuriance of the 

 product, and thus the various parts in various progress, and of varied hue, 

 tend to render these Sertularise an accurate resemblance of a pollarded 

 plantation. 



From the extraordinary effects of decay and reproduction, I have 

 seen a well-marked specimen, so completely changed in the course of a 

 few months, that unless it had been kept under constant observation, no- 

 thing could have identified it. This specimen consisted of eight or ten 

 boughs and branches originally. In the course of ten weeks all the larger 

 limbs were reduced to half their pristine length or less, by progressive 

 natural mutilation. Meantime, supervening reproduction had generated 

 above thirty new shoots from different parts, — some of them an inch 

 long ; whence, by privation and accession, the greatest alteration appeared 

 throughout. 



In one instance, an entire stem vegetated from the lower end of a 

 section which had been taken from the summit of a branch. 



Such an extraordinary diversity of aspect, not only in different speci- 

 mens, but in the same specimen, merely resulting from time and circum- 

 stances, renders it difficult to assume such indelible characters as shall dis- 

 tinguish many zoophytes. 



Both the red and the green Sertularia antennina occurring to me 

 have been always founded on shells. 



Propagation. — In the determination of genera, species, or varieties, 



