5 
Plants ; and also the well-known treatise on Insectivorous Plants . 
We perhaps learn best the influence of Mr. Darwin’s work 
on botanical science when we compare the ideas held as to 
the distribution of plants before and after the publication of 
the Origin of Species. Previously, it was generally believed 
that the different species and genera were special creations, 
and that the regions in which the same forms occurred being similar, 
had led to the creation of similar plants. This theory entirely 
failed to account for the appearance of similar plants in regions 
which had nothing in common in their physical conditions, and 
for their absence from places where the conditions were similar ; 
whereas, as pointed out by Sir Joseph Hooker, by adopting Mr. 
Darwin’s theory, “ The theory of the modification of species after 
migration and isolation, their appearance in distant localities is 
only a question of time and changed physical conditions.” 
Mr. Darwin’s geological work was chiefly the outcome of his 
voyage in the “ Beagle.” The most important of these is the masterly 
treatise On the Structure and Distribution of Coral Reefs. As with 
zoology and botany, however, his generalisations have had more 
influence than his special investigations. About the time when 
advanced geologists were beginning to feel that the old notions 
about fossils utterly failed to account for the distribution of 
organisms in the rocks, they were startled with the announce- 
ment of the theory of natural selection, and soon deeply im- 
pressed with the fact insisted on by Mr. Darwin, that the geo- 
logical record was still very imperfect. Just as this theory has 
hurried on by leaps and bounds the study of embryology, so it has 
given a mighty impulse to palaeontology. Having no longer to 
battle over what is, or what is not, a species, palaeontologists are 
now vieing with embryologists in working out the ancestral history 
of organisms. The work of Professor Marsh alone amply testifies 
as to the success of these investigations. Hot the least important of 
Mr. Darwin’s works, from a geological point of view, is his treatise on 
Vegetable Mould and Earthworms. A paper “ On the Formation 
of Mould” was read at the Geological Society in 1840. After 
more than forty years, during which period he made numerous 
additional observations and experiments, his book on Earthworms 
made its appearance — this, with the exception of two papers, read 
