CORALLINA, 233 
according to this able observer, the polyps of the same colony are all 
either male or female, and the branch is w#ésexua/; in others there 
are both male and female, when the branch is dzsexual. Finally, but 
very rarely, polyps are found uniting both sexes. 
The coral is viviparous ; that is to say, its eggs become embryos 
inside the polyp. The larva remain a certain time in the general 
Fig. 90.—Birth of the Coral Larva. (Lacaze-Duthiers.) 
cavity of the polyp, where they can be seen through its transparent 
body, as exhibited in Fig. 90. Aided by the magnifying powers of 
the microscope, coral larvae may even be examined through the trans- 
parent membranous envelope. From this position they escape from 
the mouth of the mother in the manner represented in the upper 
branch. The larva then resembles a little white grub or worm, more 
or less elongated. The larva is, however, still egg-shaped or ovoid; 
moreover, it is sunk in a hollow cavity, and covered with cilia, by the 
