Classes of Animals Without Vertebrae

These examples of perfection first established in parts of a classification.

Later, they were destroyed by others.

Then they were reestablished by the necessity and the pressure of things in the natural sciences.

Linnaeus combined several plant genera which Tournefort had previously separated such as his general polygonum, mimosa, justicia, convallaria, etc.

Now, botanists are reestablishing the genera which Linnaeus had destroyed.

In 1807, I established among the animals without vertebrae a new 10th class, the infusorians because they are not part of the polyps.

Thus, in continuing to collect the facts gained through observation and through the rapid progress in comparative anatomy, I instituted successively the different classes which now make up my distribution of the animals without vertebrae. These classes, ten in number, are arranged from the most complex to the simplest, as is the custom, as follows:

Classes of Animals Without Vertebrae

Mollusks Cirrhipeds Annelids Crustaceans Arachnids Insects Worms Radiata Polyps Infusorians

These classes constitute the necessary divisions because they are based on a consideration of the organic structure

and that, although it may be or indeed must be the case that we find in the vicinity of the limits to the classes some races, in one way or another, half way or intermediate between two classes, these divisions offer everything which art can produce which is most helpful in this sort of endeavour.

As long as our interest is in science, people must acknowledge them.

By adding to these 10 classes which divide the animals without backbones the 4 classes recognized and fixed by Linnaeus among the animals with vertebrae, we will have for the classification of all known animals the 14 following classes.

I am going to present them in an order opposite to the natural order.

Vertebrate Animals

Mammals

Birds

Reptiles

Fish

Invertebrate Animals

Mollusks

Cirrhipeds

Annelids

Crustaceans

Arachnids

Insects

Worms

Radiata

Polyps

Infusorians

Such is the present state of the general distribution of animals.

All the classes of the animal kingdom form necessarily a series of large groups according to the growing or declining complexity in their organic structure.

Should we go from simple to complex or from complex to simple?

Chapter 8 will answer this.

Nature marches in a certain direction.

A remarkable degradation is found in all organic structure if one moves from the most complex to the simplest animals.

This degradation is not nor can be finely demarcated.

Yet it exists in the main groups so evidently and consistently.

Even in the variations in the path, it depends on some general law which we should discover.