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Fig. 1.—Shell of Micraster corbovis.
“A. W. Rowe, a physician of Margate, devoted his holidays to collecting heart-urchins (Micrasters), from the Chalk of England, foot by foot. He was able to show that what appeared to be a distinct species found at the bottom of the Chalk gradually changed into different species found at the top. This change is almost imperceptible, but it can be traced in every part of the fossil shell, and it takes place in the same way in all parts of the country. Here is an example of evolution caught in the act. If we were to take a set of photographs of these fossils from the base of the series to the top, and copy them on a cinematograph film, we could see evolution taking place before our eyes.”—Dr. F. A. Bather (Creation by Evolution).
“The members of one single genus of sea-urchins would have to have been wiped out and replaced by barely distinguishable successors some dozens of times during the course of the deposition of the English chalk—if their fossils do not show descent each from a previous and slightly different ancestor.”—J. B. S. Haldane.
There is in nature no inseparable dividing line between different organic forms; for some forms there is such a gradual shading of one into the other, that it is impossible to tell where one ends and the other begins. Species are not primordial forms, fixed and impassable from the beginning; they are in fact constantly changing and new species or forms are constantly appearing.
