216 
MR. J. S. BOWERBANK ON THE ORGANIC TISSUES IN THE 
sufficiently perfect state to allow of a full and satisfactory view of their structure, 
and in many instances, the results of these examinations have been singularly inter- 
esting. I will not detail in succession the whole of these researches, but select from 
them such only as afford the best specimens of the tissues J am about to describe. 
The mode I have adopted in the examination of these specimens has been, to separate 
small pieces, about the quarter of an inch in diameter, from as nearly the termination 
of the branches or other extremities of the coral as possible, as being the most likely 
to have the animal tissues in their most perfect and efficient states, and to immerse 
these pieces in a solution of the common muriatic acid of commerce, in twelve or 
fifteen times its bulk of water. After the effervescence has ceased, the animal matter 
is usually found floating upon the surface of the fluid, in the form of an exceedingly 
delicate flocculent mass. This may then be removed, with as little alteration of form 
as possible, into some clean water in a watch-glass ; a small portion, about the one- 
tenth of an inch in diameter, should be taken from the mass with a fine pair of 
scissors, and placed in a drop of water upon a slip of glass, covered with a piece of 
very thin glass or mica. 
Upon treating in this manner some small pieces of Millepora alcicornis, I obtained 
the animal matter in an exceedingly favourable state for examination. When this 
was viewed by transmitted light with a power of 200 linear, the mass appeared 
to be composed of thin glutinous animal membranes, which frequently assumed a 
sacculated appearance, probably caused by their having been moulded into this shape 
by the polyp cells of the coral. Amid this tissue there was dispersed a complex re- 
ticulated vascular tissue, floating freely between the layers of membrane, and divi- 
ding and anastomosing without any appearance of regularity. The largest of these 
vessels averaged 5-^0 °f an inch in diameter, the smaller ramifications being about 
half that size. Those of the greatest diameter were by no means regularly cylin- 
drical, but threw off at short intervals numerous short csecoid appendages, varying 
in length from merely tubercular projections to eight or ten times their diameters, 
and terminating heinispherically without any previous diminution of size. From 
these causes, the ends of such vessels frequently assume the ramified appearance of 
a Deer’s horn (Plate XVI. fig. 1) ; other branches, instead of ending in this manner, 
continue dividing and subdividing until they also terminate in exceedingly minute 
ramifications, many of which do not exceed ^.ooo °f an inch in diameter. 
If we follow these vessels towards their larger extremities, we observe that they 
become more regularly cylindrical than that portion of them represented by figure 1, 
and at last they terminate in large cylindrical vessels of about 3 W 00 °f an inch in 
diameter. 
The smaller vessels usually enter the larger one by pairs, and a considerable in- 
crease of the diameter of the latter takes place in the immediate vicinity of the join- 
ing vessels, at the mouth of each of which there is situated a valve or diaphragm, as 
represented at a , a , fig. 2. The great vessel also has a valve at b, fig. 2. The course 
