56 GEOLOGICAL SURVEY 
organization of a well developed Gasteropod. And in this way the process from an oyster up to a 
man seems quite easy. 
But the following extract from the Teliamed of Maillet will serve as a specimen of their own 
logic on this subject. 
“ Winged or flying fish, stimulated by the desire of prey or the fear of death, or pushed ashore 
by the billows, have fallen among reeds or herbage, whence it was not possible for them to resume 
their flight to the sea, by means of which they had contracted their first facility of flying. Then 
their fins, being no longer bathed in the sea-water, were split, and became warped by their dryness. 
While they found, among the seeds and herbage among which they fell, any aliments to support 
them, the vessels of their wings being separated, were lengthened and clothed with beards; or, to 
speak more correctly, more justly, the membranes which before kept them adherent to each other, 
were metamorphosed. The beard formed of these warped membranes was lengthened. The skin 
of these animals was insensibly covered with down of the same color with the skin, and this down 
gradually increased. The little wings they had under their belly, and which, like their wings, 
helped them to walk in the sea, became feet, and served them to walk on land.” 
It is proper to state that modern philosophers of this school have given up the “appetency ” 
portion of the theory, and only insist upon a series of gradual transmutations or metamorphoses, 
such as that which the frog undergoes in its passage from the egg to the perfect animal—all the 
result of external circumstances. 
The coarse hair of the dog of warm climates, becomes fur in high northern latitudes; and the 
evergreen of the South becomes deciduous when removed to the North. What was at first acci- 
dental, in time becomes permanent. 
The setter is taught to set game, but the puppy, its offspring, sets by instinct: what was at first 
a mere habit, acquired by education, now becomes a permanent principle. 
Such facts as these, when strained beyond their legitimate application, become absurdities. Does 
it follow that because the hair of the dog is changed, to adapt it, as a covering, to external circum- 
stances, that he would ever become a lion or a monkey? or that, because the educational habits of 
the setter are transmitted to its offspring, in time it would be able to solve a problem in geometry 2? 
Yet it is reasoning very like this that those employ who teach changes by development from lower 
to higher forms of existence. 
There is a dangerous ambiguity lurking behind this word “development,” that, I am persuaded, 
has deceived many. In the geological succession of animals, there is very evident gradation from 
the lowest groups to the highest, and this has been mistaken for development. The changes that 
take place in the egg, from the commencement of incubation to the production of the living bird, 
are called development. ‘The changes that take place in the life of the insect, between the cater- 
pillar and butterfly states, are metamorphoses. Now neither of these changes can be applied to 
the gradation observed in the scale of being. 
When the frog first leaves the egg it has gills for breathing in water, a tail, and all the habits of a 
fish ; after a while legs appear, and the tail, after another short interval, disappears: the tadpole 
now begins to breathe air, and finally leaves the water, a small but well formed frog. Here is an 
example of metamorphosis, which, if it could but be seen to take place between two species, it would 
be all that could be desired to account for the gradation observed in nature. But these changes 
