CREATION BY EVOLUTION
clusion to which we were led by the study of the adult form — that the twisted body is a modification of a straight one. These crabs with the aborted abdomen must have been developed from animals — such as the shrimps and lobsters — in which the abdomen is long and normal; and so we find that in their young stages they are very much like little lobsters. If these crabs were specially created why should they begin life like lobsters?
In fact, we may lay down the general law that any member of an order or tribe that differs in structure from the other members will show in its young stages a close agreement in structure with the type prevailing in that order or tribe.
A splendid example of this law is provided by the Indian cat-fish Clarias. The cat-fishes are widely distributed over North America, Europe, and Asia, and their general appearance is familiar to most persons. With one or two exceptions all are river fish and are quite devoid of scales, having naked dark-brown or black skins, flat heads, and broad mouths. From both lips and from the corners of the mouth protrude long, slender rods called barbels, with which these fish probe the mud for the worms and other small animals on which they live. It is the fanciful comparison of these barbels to the whiskers of a cat that suggested the name cat-fish. Now one of the genera of Indian cat-fish called Clarias has learned to emerge from the water and breathe air, and in order to do this it has developed above its gills two curious tree-like organs, which are richly supplied with blood vessels. As Figure 1 shows, however, this fish is essentially like other cat-fish when it is young, but as it grows older two little buds appear above the gills on each side, which develop into the tree-like organs of the adult. Can anyone seriously doubt that Clarias has been
[ 52 ]
