1864. | Durumrs on the Formation of Coral. 621 
the polypes in direct communication with one another. It encloses 
also innumerable little calcareous corpuscles (Fig. 2, e), red in colour 
and microscopic in size; these characteristic objects enabling the ob- 
server to recognize coral even in its carliest stages. As to the polypes, 
Fia. 3. 
Part of a branch of coral, magnified and prepared so as to show the polyp-stem, p, channelled 
throughout; to each cliannel a vessel, d, corresponds; a, “ Bark,’ permeated by small vessels, c, 
putting the polypes in communication with one another; and a polype, b, drawn with ova suspended 
in the folds of the general cavity. : 
the walls of their bodies are represented by the bark itself, and their 
organs exist in the form of slender lamelle (Fig. 3, b), the edges of 
which, somewhat cushion-shaped and contorted, have a slight resem- 
blance to the convolutions of the intestinal canal. 
We have now once more to revert to the question of development, 
and to inquire how the axis or polyp-stem is formed ; the only part, as 
before said, which is available for personal decoration. The calcareous 
corpuscles of the cortex are formed soon after the young coral has 
become fixed or sessile, and on their presence depends the characteristic 
red colour. In the first instance they are equally disseminated through- 
out the tissues, but subsequently they multiply and accumulate as 
nuclei; then a red cement is deposited around them ; and these distinct 
centres, later on, not only unite with one another, but become closely 
cemented to the submarine bodies upon which the young polype has 
become fixed. This is the origin of the axis or polyp-stem. It is the 
same with young polypes as with adult branches; the latter main- 
taining at their terminal points a perpetual juvenescence, owing to 
their continued growth. And we find under their cortical covering 
a partially-formed axis bristlg@g throughout with microscopic asperities 
representing the corpuscles; these are still recognizable, imperfectly 
VOL. I. 20 
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