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Engystoma Texense, Girard — Part 6
On the sixth day (April 14th) the young tadpoles are still longer and are more curved in the egg. The body seems much thinner. The head and tail ends are unmistakable, even to the casual observer. The projections on the sides of the neck are more distinct.
On the seventh day the tail is longer and distinctly finned at its edges. The head is more distinct from the body. The projections at the sides of the neck are longer. The tadpoles occasionally move in the egg, putting the head and the tail together and then jerking them apart. They seem little changed on the following day but move more often.
On the next morning (April 17th), nine days after the eggs were laid, we find most of the tadpoles out of the jelly, clinging by two conspicuous "suckers" to the deserted jelly-mass or to water-weeds. These "suckers" are not what their name would seem to imply. They do their work of clinging, not by suction, but by means of a sticky substance or cement which they secrete. The jelly is much less stiff. Other tadpoles hatch as we watch: a vigorous wriggle, and the jelly sphere is ruptured and the tadpole becomes free. The tiny bit of life may lie flat on the jelly or at the bottom. But after a short time it is rested from the exertion and wiggles through the water aimlessly until it touches something that will act as a support. The tadpole is now about 7 3/4 mm. long, very slender and black. The transparent tail fin is conspicuous. The projections at the sides of the neck are easily seen as branched finger-like gills that have grown out from the gill plates formed five days ago. If we examine the tadpole carefully with a lens, not only can gills and suckers be seen, but prominences that are to become the eyes side view, and an opening just forward of the suckers that is to be the mouth.