238 ORIGIN AND TRANSFORMATION OF ANIMALS. 
nished with twenty or thirty slender and movable filaments.” 
M. Quatrefages compares this mode of growth to the pro¬ 
ceedings of a strawberry-plant, and thus continues the story: 
—‘^The Medusa lives some time under this form, until at 
last one horn acquires three or four times the length of its 
companions, and at the same time becomes cylindrical. A 
circular depression then forms near the crown of tentacles, 
others follow at regular intervals towards the pedicle, which 
is never reached. The body thus becomes circled with ten 
to fourteen rings.” After undergoing development, these 
rings are successively detached, and swim away. They are, 
in fact, medusoids, and gradually assume the true medusa 
form. These remarkable steps are again compared by M. 
Quatrefages to an imaginary case in the insect world. Sup¬ 
pose, for example, a butterfly laid an egg; that from this egg 
there came an earthworm, which changed into a caterpillar, 
from which other caterpillars grew like branches. Suppose, 
then, that each caterpillar retained its head, but suffered its 
body to be transformed into a chrysalis; that the body was 
then constricted at intervals, and that it gradually appeared 
to be composed of butterflies piled one on the top of another; 
that the head subsequently fell off, and the butterflies flew 
away and gradually assumed their full proportions and per¬ 
fect forms.” This certainly would be an incredible narration, 
but transfer the incidents from the insect world to the jelly¬ 
fish, and it is pretty much what actually takes place. 
The interpretation of this class of facts renders it neces¬ 
sary to bear in mind the words larva, chrysalis, and perfect 
insect, and to remember the conditions which they indicate. 
Turning to the classes of animals undergoing the peculiar 
changes which we have traced, M. Quatrefages proposes to 
adopt the nomenclature of Van Beneden, and to call scolex 
the animalcule which emerges from the egg of a Medusa, or 
any other species following the same method of reproduction. 
Extending the meaning assigned by Sars to the term sfrohila, 
it will designate every compound being which proceeds from 
a scolex, and which is destined to produce isolated indivi¬ 
duals. Lastly, borrowing from Dujardin an expression which 
he employs in a similar sense, jjroylottis will designate the 
individuals springing from a strobila, and which complete 
themselves by the acquisition of reproductive organs, and 
thus close the cycle of development.” Between the primi¬ 
tive scolex and the strobila several generations may, as we 
tlie root, and taking root at intervals, whence fresh buds are developed.”— 
llenslow, ‘ Dictionary of Botanical Terms.’ Zoologists borrow this term 
to describe aii analogous process in certain animala. 
