38 ZOOPHYTES. 



solid globular substance, with the tentacula as an irregular appendage 

 directed inwards to the old part of the specimen ; fig. 12. It will be re- 

 collected that in other ascidian zoophytes, the tentacula of orginating 

 animals have been observed as directed inwards. 



On November 23, the generating portion of figs. 10, 11, consisted of 

 four complete rows. But the form of the cells was still imperfect, nor 

 could the sides be discovered, unless by a high magnifying power ; only 

 the internal angle and two sides being visible. It is to be remarked that 

 this is the portion of latest completion. The fourth row was now formed 

 of hexagon cells. 



The embryonic hydra? were here seen in various stages. By a power- 

 ful magnifier, the body of each of the two of the fourth, or exterior row, 

 farthest advanced, was found to be obtuse, and lying outwards in the cell, 

 while the tentacula, formed like a pointed pencil, were directed inwards. 



For some time the number of embryos augmented in the cells, and 

 the progress of individuals advanced as far as the two just specified ; in- 

 deed, some of them farther, as I thought, for the ligaments uniting the 

 body to the cell seemed perceptible. Likewise the number of the cells 

 themselves increased, and these gained greater perfection, though the ex- 

 terior row, yet too young, remained always incomplete. 



In consequence of such progress, the exterior row of fig. 10, which, 

 it will be recollected, was a new generation of fig. 3, consisted of sixteen 

 cells on the 13th of November, and of forty-six in the end of Decem- 

 ber. In one or two places there were six new transverse rows. Most 

 of the embryos had disappeared without coming to maturity as hydra? ; 

 the exterior row was now less mature than previously, nor was the exter- 

 nal side of the cell well defined, though possibly almost mature. 



These and other observations proved that the true figure of the per- 

 fected cell is hexagonal, and that the increment of the product advances 

 after the same fashion as the growth of the foliaceous zoophytes. It is 

 seen also, that the embryo in its earliest visible stage is a transparent 

 spherule, next ovoidal, and that it is least advanced in the remotest or 

 newest cells. Then the body darkens, and a triangular prolongation, direct- 

 ed inwards, denotes the pencil of tentacula still closed in that form. 



