Page:Popular Science Monthly Volume 59.djvu/86

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76
THE POPULAR SCIENCE MONTHLY.

nants of the mass laid with the egg, is as yet undecided. The part of the skin of the back not taken up by these pits rises up in small papillæ, and thus each pit is closely surrounded by a ring of papillæ. From 40-114 pits are formed, and 60-70 young are developed.

Each egg thus develops inside a diminutive womb-like chamber, on the back of the mother, but as yet we do not know whether the mother supplies any nutriment to the young while it is in this protecting chamber; the arrangement of lymph and blood vessels in the skin of the mother and the organization of the young, however, raise the question whether this may not be the case. In each pit the young tadpole lies with its back toward the roof and its belly downwards. For awhile it has a large yolk-bag, or enlargement of its belly, full of nutriment and richly supplied with blood vessels; also a tail. This tail is very large, and seems to be of no use, unless it may function as a breathing organ, as in the frog of Guadaloupe, mentioned above. Another peculiarity of these favored tadpoles is that they obtain their

PSM V59 D086 Surinam tadpole and pouched marsupial frog of venezuela.png
 Fig. 11. Fig. 12.

front legs at a very early period, before their gills grow out; and thus, for a long time, appear as four-legged creatures, with most imposing tails, as represented in Fig. 11.

In this condition they break off the roofs of their little houses and each, like a baby kangaroo from its mother's pouch, peers out into the world with goggle eyes and ready hands. For nearly three months (eighty-two days) the mother is burdened like Sindbad, till the young toads jump out of their cradles and go free to shift for themselves.

Every Surrinam toad is thus launched upon its individual voyage of contest for food as a complete but small toad, and, though it had the outward symbols of tadpole life—gills and a tail—it never lived a tadpole life, with its dangers from the drying of ponds, and the chances of being swallowed alive as so many tadpoles are. Our common tadpoles may, from one point of view, be regarded as chiefly feeding phases, like the caterpillar that eats and eats to pass through the inactive chrysalis stage to the complete butterfly life. Tadpoles are phases of the frogs' lives, when almost anything can be eaten, and when there