Page:Popular Science Monthly Volume 33.djvu/764

 life, and a small bell (e), which, however, grows very rapidly, so that the animal soon assumes the adult form, shown in Fig. 9.

The life-history of this species of Cunina is given in the following diagram:

The egg becomes converted into a planula, this into a hydra, and this into a medusa, exactly as in the case of Liriope, except that the case is complicated by the budding of new hydras, each of them destined to become a medusa, from the body of the hydra which hatches from the egg, during its parasitic life, and before it becomes a medusa. Each Liriope-egg produces only one adult, while the number of adults which may be derived from a Cunina egg is quite large, although every individual in the series ultimately becomes an adult, and multiplies by sexual reproduction.

In another species of Cunina, Cunocantha parasitica, a new complication is introduced, for the hydra which hatches from the egg never becomes a jelly-fish, but remains a parasite as long as it lives, budding off other larvæ which grow up into adults. Its life-history is like this:

If the hydras which are formed by budding were to remain as hydras, like the one which hatches from the egg, and were to bud off jelly-fish, we should have a life-history which is exhibited by many species, and is shown in this diagram: