76 ZOOPHYTES. 



Both of them have been hitherto considered animals in a perfect 

 state : nor have I at any time discovered in our fresh waters any living 

 being indicating an origin from their metamorphosis : neither has pro- 

 tracted observation on themselves afforded room for conjecturing it. 



The most learned have not disdained a philosophical view of animals 

 undergoing successive metamorphoses in their advances to perfection. 

 Witness the admirable work of Lyonet on the Caterpillar of the Willow. 

 Therefore I do not hesitate to assume the subject of the following para- 

 graph, as well adapted for illustrating the general nature of many zoo- 

 phytes, and in particular, the mode of their increment — independent of its 

 own singular history. It not only elucidates the character of both simple 

 and compound genera, but it shows how a thousand individuals may ad- 

 vance from one by progressive multiplication. 



§ 1. Hydra Tuba, The Trumpet Polypus.* — Plates XIII. XIV. 



Let me here premise, that some years ago, long after the subject of 

 this paragraph had come under my notice, I submitted a few general ob- 

 servations regarding it, to the British Association for the Promotion of 

 Science, during the sittings of that learned body at Edinburgh in 1834. 

 As the study of Natural History was advancing but languidly in Scotland, 

 my principal aim was then, as on previous and subsequent occasions, to 

 engage the attention of my countrymen with the interesting phenomena, 

 which they might readily discover among our national products. There- 

 fore, selecting only the facts most easily attained, nor exacting painful and 

 protracted study, I sedulously abstained from discussing various other im- 



* Probably this is the Hydra gelatinosa of Miiller, Zoologia Danica, torn. iii. p. 25. 

 PI. XCV. Hauniw, 1789, in fol. 



In a work by a learned Norwegian author, Sars, of which I have very recently seen a 

 copious extract in M. Lesson's Acalephes, he describes what seems the same animal, under 

 the name of Strobila, I presume meaning the cone. 



From his valuable details, it appears that he was the first who revealed to naturalists 

 the remarkable metamorphosis undergone by the hydra. 



