TUBULARIA. 59 



it, on my endeavouring to describe its properties. But it seems to me 

 conclusive, that if a moving bodj, meeting an obstacle in its course, passes 

 around instead of remaining still, or if it retraces a given track, and changes 

 its direction according to circumstances, sufficient evidence is afforded both 

 of animation and of volition. 



The planula is soft and of variable form ; and it continues crawling 

 about for an indefinite time. Then its motion relaxes, it shortens and 

 thickens, and appears as if composed of two portions, a larger and smaller, 

 both very obtuse, and next it is found affixed to some solid substance. — 

 Fig. 8. 



In four days after this active creature has been discharged as a minute 

 Planaria from the vesicle of the beautiful shrub, studded with numberless 

 animated flowers, it becomes altogether metamorphosed — for now a living 

 hydra is borne on a fistulous stem with a diffusing root below. — Fig. 9. 



In the middle of November, an aged specimen, clinging to the tube 

 of an Amphitrite, bore white hydra;. All the branches were invested by 

 hundreds of clusters, composed of a number of prolific pure white vesicles 

 crowded together and resembling minute eggs. 



Another fine specimen of the product obtained towards the end of 

 September, five inches high, and apparently very old, was remarkable for 

 the profusion of pure white vesicles on the branches, which were disposed 

 in clusters of five, six, or seven together. — Plate IX. fig. 1. — The same 

 enlarged, fig. 2. 



The hydrse of this specimen were not numerous ; they were small, 

 nearly white, some of the faintest carnation. 



Within a few days, many planula?, all pure white, had been discharged 

 by the vesicles. They were of corresponding figure with the former; 

 an obtuse rounded head,* thick and fleshy body, tapering towards the tail 

 or lower extremity, which was also obtuse. — Plate IX fig. 3. 



The number of planulse continued augmenting ; but, in a short time, 

 their motion relaxed. They became stationary and quiescent, and the 

 alteration of their shape announced approaching metamorphosis. — Fig. 4. 



* By this word rounded is to be understood, not simply obtuse, but something tending 

 to a circular arc. 



