4 ZOOPHYTES. 



denotes salubrity : their ruddy hue then descends a portion of the stalk, 

 which is often longitudinally striated above, and of a rich orpiment colour, 

 fading downwards. 



The organs of prehension, nutrition, and propagation belong to the 

 hydra, or head of the Tubularia. Here also is vitality demonstrated, by 

 its turning from side to side, by the various tentacular motions, the action 

 of the oral palpi, distension of the stomach, and discharges of half- 

 digested food from its orifice, which may be held as the animal's mouth, — 

 an incident seldom witnessed. But, excepting in its own immediate vici- 

 nity, the head exercises no sensible influence over the stalk ; neither has 

 the latter any vacant cavity for its reception, as some have been led to 

 believe, from inaccurate description of the parts, nor can it be retracted. 



This Tubularia commonly occurs in society, resulting perhaps from 

 its mode of propagation, where the oldest and the youngest are approxi- 

 mated in the same group. As every separate stem enlarges insensibly 

 upwards, the intertwining roots are concentrated within a limited spot 

 below. A colony composed of 55 stalks, diverging five inches above, was 

 rooted within the diameter of an inch. None rose above six inches ; 

 32 were fine flourishing heads ; 23 stalks were vacant. Another colony, 

 occurring in 1843, consisting of 140 stalks, might have been received in 

 a vessel seven inches high, of a quadrangular form, four inches wide, and 

 under two across. The concentrated roots were limited to an area of an 

 inch and a half by an inch. Great inequality prevailed among these spe- 

 cimens, nor were any luxuriant. 



Specimens are generally founded on shells, entire or decayed, empty 

 or tenanted. The latter seldom appear. A brilliant group once occurred 

 on a shell which was carried along in its course by the crawling inhabi- 

 tant. As few vegetate on stones, the calcareous matter of shells may 

 be more favourable to evolution. 



Reproduction of the head. — Though some later naturalists object to 

 the application of the name of this portion of the animal frame, in de- 

 scribing the lower orders, it is a distinction too convenient, brief, and ex- 

 plicit, to be precipitately abandoned. 



When the head of the Tubularia has attained complete maturity from 



