Infusorians

These are infinitely small animals, with gelatinous transparent bodies, homogenous and very contractile;

They have no specially distinct interior organ, but often with oviform gemmules.

They show on the outside no radiating tentacles nor rotary organs.

This is the last class in the animal kingdom.

This is of the most imperfect animals in all respects.

Their organic structure is the simplest.

They have the fewest faculties.

They are only sketches of animal nature.

Up to now, I have combined these small animals as polyps, in the order as ‘amorphous polyps’.

They have no constant shape which is unique to all.

But I recognized the necessity of separating them to create a special class.

This does nothing to change the rank which I had assigned to them. All that results from this change is limited to a line of separation which the greatest simplification in their organic structure and their lack of radiating tentacles and rotary organs seem to require.

The organic structure of infusorians becomes increasingly simple.

This last of the genera is the limit of animal nature.

At least, the animals display the limit which we can reach.

Particularly in the animals of the second order of this class, it is certain that all traces of the intestinal canal and mouth have disappeared entirely, that there are no organs at all, in a word, that they no longer carry out digestion.

The infusorians are:

• very small gelatinous bodies, transparent, contractile and homogenous
• made up of cell tissue almost without any consistency, yet nevertheless irritable at all points.

These small bodies, which appear only animated or moving points, nourish themselves by absorption and a constant water intake.

Undoubtedly they are animated through the influence of subtle ambient fluids, like heat and electricity, which simulate in them the movements which make up their lives.

In considering such animals, if we were still to assume that they possessed all the organs which we know about in other animals but that these organs are based in all the points of their bodies, how vain would such an assumption be!

In fact, the extremely weak (almost nonexistent) consistency of the parts of these small gelatinous bodies indicates that such organs must not exist, because it would be impossible for them to carry out their functions.

In order for any organs to have the power to react upon fluids and to exert their appropriate functions, their parts must have the consistency and the tenacity which can give them force; now, this is precisely what cannot be assumed in connection with the frail animals under discussion.

Only among the animals of this class does nature appear to create spontaneous or direct generations, which she renews continually whenever circumstances are favorable for that.

We will try to show that by spontaneous generations nature has acquired a way to create indirectly, after the passage of an enormous time, all the other races of animals which we know about.

What justifies our thinking that the infusorians or the majority of these animals owe their existence purely to spontaneous generations is that these frail animals all perish in the low temperatures brought on by the bad weather seasons.

Surely we will not assume that such delicate bodies can leave any bud with sufficient consistency to preserve itself and to reproduce in warm seasons.

We find the infusorians in stagnant waters, in the infusions of plant or animal substances, and even in the reproductive liquid of the most improved animals.

We find them exactly alike in all parts of the world, but only under circumstances where they could be created.

Thus, by considering successively the different systems of organic structures in animals, from the most complex right to the simplest, we have witnessed the degradation in that structure start in the very class which includes the most improved animals, then later progressively advance from class to class, although with anomalies produced by various sorts of circumstances, and finally, end in the infusorians.

These last are the most imperfect animals, the simplest in organic structure, and those in which the degradation which we have followed has reached its limit, by reducing the animal’s organic structure so that it consists of a simple body, homogenous, gelatinous, almost without consistency, without special organs, and uniquely formed from a very delicate cellular tissue, hardly sketched out, which appears to be brought to life by subtle ambient fluids which penetrate it and move out again constantly.

We have seen the successive process by which each particular organ, even the most essential, gets degraded little by little and finally goes away and disappears entirely long before reaching the other end of the order which we are following. And we have noticed that it is principally in the invertebrate animals that we see particular organs done away with.

To be sure, even before leaving the vertebrate division, we already perceive great changes in the improved condition of the organs, and some of them, like the urinary bladder, diaphragm, vocal organ, eyelids, and so on, even disappear totally. In fact, the lung, the most improved organ for respiration, begins to be degraded in the reptiles and ceases to exist in the fish, never to reappear in any invertebrate animal.

Finally, the skeleton, the basis for the four extremities or limbs which the majority of vertebrate animals possess, begins to deteriorate, mainly in the reptiles, and is completely finished in the fish.

But it is in the division of invertebrate animals that we see the disappearance of the heart, brain, gills, conglomerate glands, the vessels appropriate for circulation, the organs for hearing, sight, sexual generation and even of feeling, as well as those for movement.

It would be vain for us to seek out in a polyp, for example in a hydra, or in the majority of animals of this class, the least vestiges of nerves (organs of feeling) or muscles (organs of movement).

Only irritability, with which every polyp is very clearly endowed replaces in it both the faculty of feeling which it cannot possess (because it does have any organ essential for that) and the faculty of voluntary movement (because all voluntary action is an act of the organ of intelligence and this animal totally lacks any organ like that).

All its movements are the necessary results of impressions received in its irritable parts, exterior stimuli, and are carried out without any possibility of choice.

Put a hydra in a glass of water and place this glass in a room which does not receive light except through a window (hence, from a single side).

When the hydra is established on a point of the sides of the glass, turn the glass in such a manner that the daylight strikes another point opposite to the one where the animal is located.

You will always see the hydra go in a slow movement to take up a position in the place where the light strikes and stay there for as long as you do not change the point.

In doing this, the hydra follows what we see in the parts of plants which arrange themselves, without any act of will power, towards the quarter from which light comes.

Wherever a particular organ no longer exists, the faculty which it gives rise to also ceases to exist.

But, in addition, we see clearly that to the extent that an organ deteriorates and gets smaller, the faculty deriving from it becomes proportionally more obscure and imperfect.

Thus, as we descend from the most complex toward the simplest animals, the insects are the last animals in which one finds eyes. But we have every reason to believe that they see very obscurely and make little use of their sight.

The degradation in organic structure and of each organ (right to their total disappearance) is a reliable fact.

This degradation is even in the nature of the fluids and flesh of animals.

The flesh and blood of mammals and birds are the most complex and vital materials.

After fish, these materials progressively deteriorate to the point that soft radiates, polyps, and above all in the infusorians:

• the essential fluid is like water
• their flesh displays only a gelatinous material, hardly animalised.

This soup of such flesh would be not nourishing and strengthening for the person who eats it.*

Notes to Chapter Six

1. Birds have pierced lungs and feathers for hair as a consequence of them flying.

People ask me why the bats do not also have feathers and pierced lungs?

Bats have a systematic organic structure more perfect than that of the birds. This includes a complete diaphragm which limits the enlargement of their lungs.

This prevents pierced lungs nor to puff themselves up with air sufficiently so that the influence of this fluid, with effort reaching the skin, gives the horny material of the hair the faculty of branching out into feathers.

In fact, in the birds, the air, once introduced right into the bulb of the hairs, changes their base into a tube and forces these very hairs to divide themselves up into feathers. This could not have happened with the bat, where the air does not penetrate beyond the lung.

2. The Anatifa, Balanus, Coronula and Tubicinella

3. “It is above all in the spiders that the heart is easy to observe. We see it beat through the skin of the abdomen in the non-hairy species. In lifting up this skin, we see a hollow organ, oblong, pointed at two ends, the anterior end pointing towards the thorax, on the sides of which two or three pairs of vessels can be seen leaving.” Cuvier, Anatom. Comp. Vol. IV, p. 419.