226 EVOLUTION IN BIOLOGY VI | 
and of the Carnivora have been almost as closely 
followed through the Tertiary deposits; the gra-_ 
dations between birds and reptiles have been 
traced ; and the modifications undergone by the 
Crocodilia, from the Triassic epoch to the present 
day, have been demonstrated. On the evidence of 
paleontology, the evolution of many existing forms 
of animal life from their predecessors is no longer 
an hypothesis, but an historical fact ; it is only the 
nature of the physiological factors to which 
that evolution is due which is still open to dis- 
cussion. 
[At page 209, the reference to Erasmus Darwin does not do 
justice to that ingenious writer, who, in the 39th section of the 
Zoonomia, clearly and repeatedly enunciates the theory of the 
inheritance of acquired modifications. For example: ‘‘ From 
their first rudiment, or primordium, to the termination of their 
lives, all animals undergo perpetual transformations ; which are 
in part produced by their own exertions in consequence of their 
desires and aversions, of their pleasures and their pains, or of 
irritation, or of associations ; and many of these acquired forms — 
or propensities are transmitted to their posterity.” Zoonomia I., 
p- 506. 1893.] ‘ 
ee ee a ee 
