XIII. On the Organic Tissues in the Bony Structure of the CoralUdce. 
By J. S. Bowerbank, Esq., F.G.S. Communicated by Thomas Bell, Esq., F.R.S. 
Received April 19, — Read April 21, 1842. 
The polyps of the numerous species of the Corallidoe have been known and described 
many years, but I am not aware that their connection with each other has been traced 
through the solid masses of their calcareous skeletons, or that the nature and struc- 
ture of the animal tissues of these parts have, to the present period, been figured or de- 
scribed by any author. Ellis, in his History of Corallines, published in the year 1755, 
has described the mode he adopted in the examination of the calcareous axes of some 
of the subjects of his observations, and has mentioned in several places in his work, 
that he had subjected them to the action of vinegar, but he does not in any instance 
minutely describe the results obtained by this application, nor does he describe any 
organic tissues or results, further than that he thus obtained the animal substance of 
the skeleton, freed from the calcareous matter previously combined with it. That 
so accurate, acute and industrious an observer, should not have seen and described 
more of the minute organic tissues which are now with our improved means readily 
to be distinguished in the tribe of animals that formed the objects of his investiga- 
tions, is only to be accounted for by the want of instruments competent to observe 
tissues of such extreme delicacy. 
My attention has been drawn to this subject from having ascertained, in one of 
the sponges of commerce, and in several species of sponges from Australia, the 
existence of a very minute and beautifully ramified vascular tissue ; and in some 
cases of the occurrence of molecules of extreme minuteness within those vessels 
which appeared to me to be analogous to those of the circulation in the higher tribes 
of animals. These facts I had the honour of laying before the Microscopical Society 
of London, on the 27th of January 1841. The occurrence of such tissues in the 
horny skeletons of animals so low in the organic scale as the Spongiadse, naturally 
suggested the idea of the probability of the occurrence of similar or more fully de- 
veloped tissues in the skeletons of the higher tribes of zoophytes ; and I accordingly 
determined to pursue the investigation, with the hope of adding, in some slight 
degree, to our knowledge of the organic structure of the bony portions of the Coral- 
lidse, and also of throwing, if possible, further light upon the still contested place in 
the scale of created beings of the sponge tribe. With this view, I submitted small 
portions of nearly seventy species of bony corals to the action of dilute muriatic acid, 
and from thirty-five of these I have succeeded in obtaining the animal tissues in a 
