The Importance of Considering Affinities

The affinities in plants are determined solely by the parts essential for reproduction. The importance of these parts are ranked as:

1. The embryo, its accessories (the cotyledons, the perisperm), and the seed which contains it;

2. The sexual parts of flowers, such as the pistil and the stamens;

3. What surrounds the sexual parts; the corolla, the calyx, and so on;

4. The seed casing, or the pericarp;

5. The reproductive bodies which do not need any pollination.

These principles give a new consistency and a reliability to the natural sciences.

The affinities which have been determined by conforming to such principles are not subject to variations of opinion.

After realizing the importance of affinities, people have recently created the ’natural method'.

• It is only the sketch traced by man of the route nature follows to brings its productions into existence.

In France, it is no longer a question of those artificial systems based upon characteristics which jeopardize the natural affinities between the objects subjected to such systems, ones which establish division and distributions detrimental to the advancement of our knowledge about nature.

In animals, we can determine the natural affinities only through their organic structures.

Consequently, zoology can determine these affinities from comparative anatomy.

These affinities are from the works of the anatomists, and not always the conclusions from those facts.

For too often, these conclusions encourage opinions which lead us astray.

When someone discovers any new fact, he hurls himself to assign a cause to it.

• His imagination is so fecund in the production of ideas.
• He does not guide his judgments by the totality of facts.

A genera are groups of species that have certain limits based on natural affinities which are the basis for interrelationships

Genera form families according to affinities.

Families form orders.

Orders have classes.

Finally, these groups divide up each kingdom into its principal sections.

Therefore, the well-determined natural affinities must guide us in forming our collections.

We divide each kingdom into classes

• Each class into orders
• Each order into sections or families
• Each family into genera
• Each genus into species

The total series of beings making up a kingdom represents the order of nature.

However, it is important to bear in mind that the different types of divisions which we must establish in this series so that we can know the objects in it more readily are not part of nature at all and are truly artificial, although they display portions of the same order which nature has set up.

If we add to these considerations the points that in the animal kingdom the affinities must be determined mainly according to organic structures and that the principles which we must use to establish these affinities must not leave the least doubt about what they are based on, we will have, in all these matters, solid foundations for zoological philosophy.

It is futile for naturalists to waste their time in describing new species, seizing upon all the slight modifications and the small particularities of their variations to augment the immense list of species drawn up in a list, in a word, setting up genera in various ways and constantly changing the analytical principles used to characterize them.

If science neglects philosophy, its progress will not be real, and the entire work will remain imperfect.

It is really only since we set about establishing the close or distant interrelationships existing among the various natural productions and among the objects comprising the different groups we have created among these productions that the natural sciences have acquired some reliability in their principles and a philosophy which turns them into real sciences.

How much our arrangements and our classifications would improve each day from the sustained study of the affinities among objects.

By studying affinities, I became convinced that:

• the soft ones, like the medusas and other neighbouring genera which Linnaeus and even Bruguière placed among the mollusks, are essentially like the echinoderms and should form a special class with them.
• the infusorian animals could no longer be grouped with the polyps in the same class
• the radiates must no longer be confused with the polyps
• the worms form an isolated group
• the arachnids could no longer be a part of the class of insects
• the cirrhipedes were neither annelids nor mollusks

By studying affinities:

• I was able to improve the arrangement of mollusks
• I recognized that the pteropods, although distinct:
  • are nearly related to the gasteropods
  • must be placed between the acephalic mollusks, to whom they are close, and the gasteropods.

These pteropods have no eyes, like all the acephalids, and almost always lack a head.

Even the Hyalae have only the appearance of one.

The study of affinities is the most important of those which can advance the natural sciences.