338 Mr. Hatchett's Experiments on Zoophytes, 



crucible. The dark brown horny parts swelled, and puffed up, 

 with much smoke, and a smell like that of burned horn. 



The coralline joints also emitted the same smoke and smell, 

 and became dark gray. 



When put into dilute nitric acid, a solution was made, with 

 effervescence, during which, there was a copious deposition of 

 animal coal. 



From this solution, nothing but carbonate of lime was ob- 

 tained by the usual precipitants. 



A tube of membrane invests the curious structure of the Isis 

 ochracea ; but no such tube or outer coat exists in the Ids Hip- 

 puris ; for the coralline joints (like some of the Madrepores, 

 Millepores, &c.J consist of a membranaceous substance, hardened 

 by carbonate of lime, and the only difference appears to be, 

 that in the Madrepores and Millepores, the membranaceous part 

 is less compact and abundant ; but, even the striae of the coral- 

 line joints remain visible, and unchanged, in the membrane of 

 this Isis. 



The brown horny part forms also a marked characteristic 

 in this Isis, and seems to approach it to certain of the Gor- 

 gonia. 



This horny part does not however pervade the whole of the 

 branch ; for, where the coralline joints commence, this horny 

 substance immediately terminates, internally as well as exter- 

 nally, and is not to be discovered but between or in the separa- 

 tion of these joints. 



Gorgonia nobilis. 



I next proceeded to examine the Gorgonia nobilis or red coral; 

 and, of this, I separately subjected to experiment different pieces, 



