60 ZOOPHYTES. 



Here, as before, they seemed forming into two portions. Meantime a root 

 was diffusing below, and a stomach forming above, fig. 5 ; and the higher 

 portion by the gradual refining and improvement of the parts was deve- 

 loped as a perfect Tubularia. — Fig. 6. 



The progress of this zoophyte is rapid ; sometimes the nascent hydra 

 flourishes in six days after the discharge of the planula from the vesicle. 

 It is now furnished with from 12 to 18 very muricate tentacula, for the 

 number is variable in individuals. Indeed, there is almost a common and 

 singular irregularity of the subordinate parts, not only in the nascent, but 

 in the mature hydra of many zoophytes. From such extraordinary irre- 

 gularity or variety of aspect, it is less surprising that considerable diffe- 

 rences are seen in the figures presented by authors, besides which there 

 may be some difference in the aspect of the same species of animals found 

 in various countries. Yet it is not to be denied that many imperfections 

 orio-inate, first, from neglect in selecting the finest specimens, secondly, 

 from inability to obtain the service of competent artists. Let it be re- 

 membered that an alteration of the position of a subject will often bring 

 a whole series of organs into view which were previously unnoticed. 



The formation of the root of the Ttthularia raii/en is definite and con- 

 spicuous — generally forking from the centre into four radicles, full of pith 

 like the stem, which extend far, and occasionally exhibit a subdivided ex- 

 tremity. Four radicles seem the regular complement. Herein is a great 

 distinction from the Tubularia proper, and a strong analogy with the Ser- 

 tularia. I mean in the formation of the root. 



I am not aware that there is any essential difference between the 

 nascent animal from the yellow vesicle and that from the white vesicle. 

 The root of the former seemed diffusing amidst a transparent matter, which 

 from colour might be inconspicuous in the latter. We shall afterwards 

 find some correspondence in these points with the Sertularia. 



Both nascent products from the yellow and the white planula rege- 

 nerate the hydra. That of a nascent specimen from a yellow vesicle sub- 

 sisted 23 days ; in 10 days from its fall, it was replaced by one which 

 subsisted 4 or 5. 



The position and aspect of the vesicles are represented Plate VIII. 



