CAMPANULARIAN ZOOPHYTES. 129 



is by no means a phenomenon of unfrequent occur- 

 rence in this remarkable class, and yet, until a very 

 few years ago, such a circumstance in their history was 

 not only entirely unknown, but, when first announced 

 to exist, the discovery was received by naturalists with 

 as much hesitation and jealous caution, as if some 

 visionary enthusiast had endeavoured to impose upon 

 their credulity. 



Animal magnetism and table-turning found ready 

 advocates ; the upholders of clairvoyance and spirit- 

 rapping had no difficulty in making converts to their 

 mysteries; but to believe that a polyp could give 

 origin to a jelly-fish, or a jelly-fish to a polyp, was 

 esteemed to be an assertion so incredible, that nothing 

 but the well-known simple truthfulness of its first 

 discoverers could have obtained a hearing in support 

 of statements apparently so monstrous and absurd. 



" If, in a picture, Piso, you should see a horse's body 

 with a fish's tail, and limbs of beasts of the most 

 different kinds covered with feathers of all sorts of 

 birds, would you not laugh, and think the painter 

 mad"*?" was a question easily propounded, and still 

 more readily answered, until at length the notion 

 of these alternations of form in the Hydrozoa might 

 have been scouted as incredible and preposterous, had 

 not the evidence of our own senses, the aquarium 

 and the microscope, asserted the reality of the fact, 

 and compelled the belief of the most sceptical : 

 " Serpentes avibus geminentur, tigribus agni." 



The subject of the present chapter affords us an- 

 other opportunity of elucidating this wonderful pro- 

 * Horace, De Arte Poetica, freely translated. 



G5 



