1864. ] Dorturers on the Formation of Coral. 619 
or to objects with which they may como into contact ; this tendency is 
favoured, too, by their mode of progression. Thus, even their activity 
is a principal cause of their losing the freedom of movement, from its 
favouring the close adhesion of the posterior part of the body—that 
part which will ere long be the analogue of the base of the Actiniz and 
other adult Zoanthidee. This proneness to apply themselves to other 
objects appears specially manifested when the elongated or vermicular 
form is about to disappear; then the embryos sink down upon them- 
selves, and losing in height what they gain in breadth, change their 
form into that of small lens-shaped dises (Fig. 1, ¢), in the middle of 
which the more slender extremity, bearing the mouth, buries itself, 
and becomes surrounded by a circlet of little cushions. Upon these 
cushions, and consequently around the mouth, eight small nipple-shaped 
projections very soon show themselves; these are covered by delicate 
processes, which subsequently become by elongation the arms of the 
polype (Fig. 1, f). Whilst carefully examining with a lens the stones 
brought from the bottom of the sea by the nets of the coral fishers, I 
found little red objects, a quarter and even a half of a millimétre in 
diameter, which a microscopic investigation showed to be the young 
bases of coral. Smaller than those which had been formed and fixed 
in my aquaria, they only as yet enclosed one single animaleule. By 
further search I was able to follow out all the stages intermediate 
between the most simple individuals and the most complex branches. 
Afterwards retracing my steps, I could pursue my inquiries up to the 
point of the most complete development. 
Soon after the young polype has fixed itself, and when its ten- 
tacles have become well developed, its white colour disappears, giving 
place to the characteristic red of coral. (Fig. 1, f, represents a young 
polype of half a millimctre in diameter.) It is difficult to depict the 
delicacy and elegance of the animal at this stage of its growth. The 
base or body is of a beautiful rose-colour, while a white coronet formed 
by the arrangement of the tentacles occupies the upper part. It some- 
times presents the illusion of a charming white flower, with its graceful 
petals surmounting an urn. 
When the first animal, the development of which we have just 
traced, is complete, a new phase of growth is entered upon. There 
appear, one by one upon its sides, small nipple-shaped projections, 
true buds or gemma (Tig. 2, b, d), having their origin in the very 
tissues of the animal, and provided with a single orifice covered with 
tentacles; these at length become transformed into so many new 
polypes, fac-similes of the original animal. 
These outgrowths do not separate themselves from the original 
stock; and since they in their turn become centres from which bud- 
ding takes place, we may well understand how rapidly the whole 
number will increase. 
This peculiar faculty of increasing by budding is shared by the 
corallines with vegetables; and to it must be referred the formation 
of branches and twigs, and the increase in length of the parent stems. 
But a distinction must be drawn between the multiplication of the 
number of bases or branches of coral and the increase in number of 
