. Degeneration : a chapter in Darwinism. Degeneration; Evolution. DEGENERA TION. 41 My object in the next place is to show that the structure and life-history of these Ascidians may be best explained on the hypothesis that they are instances of degeneration ; that they are the modified descendants of animals of higher, that is more elaborate structure, and in fact are decreneratc. Fig. 15.—Anatomy of an Ascidian (Phallusia). At the top is the mouth, to the right the orifice of the cloaca. In the cloaca lies an egg, and above it the oblong nerve ganglion. The perforated pharynx follows the mout
. Degeneration : a chapter in Darwinism. Degeneration; Evolution. DEGENERA TION. 41 My object in the next place is to show that the structure and life-history of these Ascidians may be best explained on the hypothesis that they are instances of degeneration ; that they are the modified descendants of animals of higher, that is more elaborate structure, and in fact are decreneratc. Fig. 15.—Anatomy of an Ascidian (Phallusia). At the top is the mouth, to the right the orifice of the cloaca. In the cloaca lies an egg, and above it the oblong nerve ganglion. The perforated pharynx follows the mouth and leads to the bent in- testine which is seen to open into the cloaca. The space around the curved intestine is the body-cavity ; in it are seen oval bodies, the eggs, and quite at the lower end the curved heart. The root-like processes at the base serve to the Ascidian to stones, shells, or weed. Vertebrata, standing in the same relation to fishes, frogs, and men, as do the barnacles to shrimps, crabs, and lobsters. The young of some, but by no means of all these. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Lankester, E. Ray (Edwin Ray), Sir, 1847-1929. London : Macmillan and Co.
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