The Theory of Evolution 43 
least, the fossils have been found in the same part of the 
world, so that there is less risk of arranging them arbitrarily 
in a series to fit in with the theory. 
EVIDENCE FROM DIRECT OBSERVATION AND EXPERIMENT 
Within the period of human history we do not know of a 
single instance of the transformation of one species into 
another one, if we apply the most rigid and extreme tests 
used to distinguish wild species from each other! It may 
be claimed that the theory of descent is lacking, therefore, 
in the most essential feature that it needs to place the 
theory on a scientific basis. This must be admitted. On 
the other hand, the absence of direct observation is not 
fatal to the hypothesis, for several reasons. In the first 
place, it is only within the last few hundred years that 
an accurate record of wild animals and plants has been kept, 
so that we do not know except for this period whether any 
new species have appeared. Again, the chance of observing 
the change might not be very great, especially if the change 
were sudden. We would simply find a new species, and 
could not state where it had come from. If, on the other 
hand, the change were very slow, it might extend over so 
many years that the period would be beyond the life of an 
individual man. In only a few cases has it been possible 
to compare ancient pictures of animals and plants with their 
prototypes living at the present time, and it has turned out 
in all cases that they are the same. But these have been 
almost entirely domesticated forms, where, even if a change 
had been found, it might have been ascribed to other fac- 
tors. In other cases, as in the mummified remains of a few 
Egyptian wild animals (which have also been found to be 
exactly like the same animals living at the present day), 
1 The transformation of “smaller species,” described by De Vries, will be 
described in a later chapter. 
