138 ZOOPHYTES 



CHAPTER VII. 



ASCIDIA. 



As an introduction to one great section of the race of Zoophytes, a 

 few words have been already said of the genus Ascidia, an animal very 

 common in our seas, though the nature of none is less known in its details. 

 We have seen an animated being bearing some analogy to it in several 

 important features, combined as well with other organic as inorganic 

 parts. But what shall now be briefly said, applies to the Ascidia as 

 simple in itself, and void of all foreign combinations. 



Naturalists are very little acquainted with the history of this creature 

 in its living state ; nor can I add any illustrative observations of material 

 consequence ; yet, with sufficient care, the Ascidia may be easily preserved 

 a considerable time in captivity. Neither does it belong to a tribe of 

 transient existence ; on the contrary, it seems to be a long-lived animal. 

 If observers find the safety of such creatures precarious, it is from their 

 having previously suffered some unseen injury. Thus pressure is always 

 pernicious, and without frequent change of its native element, mould is 

 readily generated on the surface of the skin. Inveterate enemies are found, 

 besides, in more than one species of the smaller bivalve shells, which, pene- 

 trating the flesh, render it their permanent abode, or abandon it at will. 



Most of the Ascidise are coarse, unsightly, deformed looking animals, 

 utterly void of that external symmetry and beauty rendering many of the 

 tenants of the waters so interesting. Nor is it in this only, that they 

 should fail to attract the spectator's notice. They testify neither instinct, 

 action, nor motion, nor even the symptoms of life, farther than slight en- 

 largement and reduction of size, together with contraction and expansion 

 of the two tubular orifices of the body. No sensible alteration follows 



