The Natural Order of animals

Chapter 5 said that the essential aim of a distribution of animals must not limit itself to the possession of a list of classes, genera, and species.

This distribution must display the means most favorable to the study of nature.

However, our general distributions of animals today have a structure which reverses the very order nature.

It moves from the most complex towards the most simple.

• This makes the learning of the composition of organic structure more difficult to grasp.

We perceive less easily:

• the causes of this progress
• the interruptions in it

When we realize that something is useful, we hurriedly make use of it, even though it is contrary to custom.

The current custom is to put:

• at the head of the animal kingdom the most perfect animals
• at the end the least perfect and simplest

This is from our tendency to give precedence to the objects which we find striking, pleasing, or interesting.

• We have preferred to move from the best known towards the least known.

These considerations were very persuasive.

But they should yield now to scientific needs, particularly to the need to facilitate our progress in the understanding of nature.

Nature began exclusively with the simplest structures.

Botanists first gave zoologists the example of the true order of nature.

They formed the first class of plants with the acotyledonous or agamous plants.

These:

• are the structurally simplest, most imperfect plants
• had no cotyledons, no determinable sex, no vessels in their tissues, plants which are composed only of cellular tissue more or less modified according to different extensions

What the botanists have done with plants, we should do with animals.

This is because the natural order of classes is determined by the growing complexity in organic structure.

• This is much easier to see among animals than in plants.

This order of nature will:

• make the study of objects much easier
• improve our understanding of:
  • the organic structure of animals
  • the progress in its complexity from class to class
• will demonstrate better the affinities between the different degrees of animal organization and the external difference used to characterize the classes, orders, families, genera, and species

Nature would make only either create only one race in each organic order or one race for the simplest animals and plants if nature:

• could not make organic structures last forever
• could not give these bodies the capacity of reproducing

Thus, the only thing nature had to produce directly without the combination of any organic action was the simplest organic bodies.

Nature gave these bodies which she herself created the capacity to:

• feed themselves and grow
• preserve the improvements they acquired
• multiply and pass on these same capacities through reproduction over time

This allowed those bodies to produce diversity, one after the other.