. .[ 45 ^ ] 
part. Thele principles referable thofe drawn from 
human fcull, hartfhorn, and other parts of animals. 
After the accounts here laid down, we are able to 
afiign the reafons of all the particular facts we ob- 
ierve in coral. We fee, why a branch thereof, 
broken off and detach'd from its Item, may flourifh. 
It is became the coral-infeCts, which are contain’d in 
its cells, not having been injured, continue their 
operations ; and drawing no nouriihment from the 
Item of the coral, are able to increafe, detached and 
leparate. * How they live and are nourished, is pro- 
poled to be explain’d in treating of the urtica of the 
Madrepora, in which thefe animals are vaftly larger, 
and appear very diftinCtly. # 
In each hole or liar of the Madrepora, on which 
our author lays the evident proof of his new fyftem, 
the urtica, placed in the centre of each pore, caufes 
it to increale in every direction, by lifting itfelf fur- 
ther and further from the centre of the ftone. And 
in coral, and in the lithophyton, the urtica, being- 
niched in their crufts or barks, depofits a juice or li- 
quor, which runs along the furrows perceiv’d upon 
the proper fubftance or body of coral, and, flopping 
by little and little, becomes fixed and hard, and is 
changed into ftone ; and this liquor, being flopped 
by the bark, caufes the coral to increafe proportion- 
ally, and in every direction. In forming coral, and 
other marine productions of this clafs, the animals 
labour like thofe of the teftaceous kind, each accord- 
ing to his fpecies, and their productions vary accord- 
ing to their feveral forms, magnitudes, and colours. 
If, after what has been here laid down, fomewill 
flill confider thefe marine productions as plants, they 
are 
