Fropagation amovg the Lower Animals. 157 



many afford a more favourable opportunity for observation, "by 

 their horizontal or oblique position. Angular projections soon 

 issue from the front of the head ; and by means of their contact 

 with the neighbouring surface of the vessel, adhesion ensues. 

 While apparently slight, the animal struggles to free itself, but 

 it beconies rooted also as a preliminary to its metamorphosis. 

 The upright tail disappears, and a central yellowish nucleus re- 

 mains soon converted to the palest green. 



Meanwhile eight, or about that number, of radicles are is- 

 suing from the circumference of the nucleus, diffuse themselves 

 on the glass amidst a thin transparent matter, by the outline of 

 which they are bounded. In eight days two orifices with circu- 

 lar lips have opened above into the cavity of the nucleus, and 

 through one of these the pulsation of a large internal vessel may 

 be distinctly seen, together with the course of dark atoms, dis- 

 tributed along with a circulating fluid through numerous chan- 

 nels to remoter parts. Buoyant particles are next absorbed, 

 and pellets ejected. Another ascidia has been produced. 



But this animal is only the first of a group which shall be 

 formed of hundreds. Whether it be the centre of a system 

 of animals into which the eight radicles shall develope I cannot 

 affirm positively. The specimen itself seemed to be composed in 

 some parts of eight or more ascidiae surrounding a central de- 

 pression, not unlike the superficial depressions appearing in the 

 sponges of commerce. Naturalists speak of a system or set of 

 animals composing analogous products, though imperfectly ex- 

 plained or understood for want of observation as living specimens. 

 Instead of disappearing as in the preceding ascidia, the radicles 

 enlarge here into an oval leaf affixed below, where the nucleus 

 is connected with it by an attenuating channel. I call it a 

 channel, for at a certain stage, when a month old, the circula- 

 tion is evidently carried on between the nucleus and the enlar- 

 ging radicles. But there is the same difficulty of preserving 

 these subordinate parts as of preserving the young tubularia?, 

 or flustra?. They have too little consistency for their feeble life 

 to resist the injurious consequences incident to so artificial aeon- 

 dition as attends removal from their natural site. The nucleus 

 readily survives : it seems then to become double, and a smaller 

 ascidia buds from each of the two. Five or six were generated 

 thus, from one, in ten weeks. 



