involving the masses of the Planets, their distances, and their times of rotation. I shall return to this subject in a following note (No. VII.); and I only remark by the way, that should these analogies be hereafter so far confirmed as to become an accepted law of our System, they seem not to have any very obvious bearing on the hypothesis discussed in this Note.

No. II.

On Animal Creations by Galvanism.

(p. xxv.)

WHAT are we called on to believe when we are told of the galvanic creation of an Acarus? That galvanic forces can, without the help of any pre-existing vital germ, at once assemble together the particles of dead matter, and arrange them in the complicated organic structure of an Acarus; and that the same forces can give this organic structure all the attributes of life, and the powers of reproduction. We know something of elective affinities, and we can modify these affinities by new modes of galvanic action. We can produce definite compounds, and definite crystalline forms, out of the definite combinations of dead and inorganic particles. But the formation, in this way, of a complicated organic structure is nothing less than a miracle, unless we suppose the pre-existence of some vital germ among the particles on which we experiment: for it refers to one system of causation effects that are most widely apart in all their manifestations; and it is utterly abhorrent from all our experimental conceptions of chemical action and molecular arrangement.

I do not believe that galvanic action can give any of the true attributes of life to the particles of dead and inorganic matter and if (only for the sake of argument) we were to give up this point, and assume at once-with Lamarck,

Oken, and other materialists-that organic life may begin by the direct action of the galvanic fluid on certain gelatinous forms of matter that is dead and inorganic, what should we gain by the assumption? On this assumption, life begins only in the very lowest organic forms of nature, multiplies afterwards by fissiparous generation, and then rises gradually on some line, or lines, of the organic scale, by progressive development. On no sane view of this theory can we produce an Acarus experimentally from dead matter without a long ascending process of development— a process implying many specific transmutations, and many transcendental leaps from Order to Order. To derive an Acarus at once from inorganic matter is, therefore, just as abhorrent from any rational view of the theory of development, as it is abhorrent from any known law of atomic combination.

That there are difficulties in accounting for the generation of some of the very humble forms of organic life, no one pretends to deny. It is surely the part of wisdom to be guided, in all such cases, by the analogies that are presented to us by other parts of nature which are neither obscure nor doubtful. In this view, we do not reject, but we vindicate, the grand uniformity in the organic laws of nature. At any rate there is no wisdom in explaining the obscurest phenomena of organic life by hypotheses which utterly shut out the light given to us by the help of analogy.

Multiplied blunders were made by those who first told us of the galvanic creation of an Acarus. Its species was mistaken-its exuvia were mistaken for its ova. It was affirmed that its ova could not be transported through the air because of their size and gravity. Other spurious organic creations were asserted, &c. &c. The transporting power of the air is sufficient to bear bodies, that are specifically heavy (provided they be in a state of great comminution), to vast distances. The air teems with the invisible

seeds of animal and vegetable life, that are borne mechanically on its wings, and begin to germinate the moment they fall on a spot fitted to call forth their organic functions. The specifically heavy siliceous castings of microscopic Infusoria are probably borne, as we learn from Ehrenberg, across the Atlantic to the coasts of Africa and Europe; and they are certainly borne, in millions of millions, from the interior of Africa to the southern coasts of France and Italy. This transporting power of the air at once explains many of the supposed cases of spontaneous generation.

Again, we know that some of the lower forms of the animal kingdom are so tenacious of life that they will endure, without vital injury, the extreme temperatures of boiling water and long-continued polar frost: and we also know that the ova of these low animals are far more tenacious of life than the animals themselves. In such facts as these we have an explanation of many cases of supposed spontaneous generation, and of experiments that pretend to teach us conclusions that violate all our experimental knowledge of molecular action, and all the best analogies of the living world.

No. III.

On the Placoïd and Ganoïd Fishes of the Paleozoic Strata, and their places in the Organic Scale.

(Supra, p. lxv. p. lxxi. and p. cccxxiii.)

THE claims of the Cestracion (to which some of the oldest fossil fishes are very nearly allied) to a high rank in the scale of its Class, rest on the following facts:

1. Its cerebellum is absolutely and relatively larger than in the great bulk either of osseous or of cyclostomous Fishes; and its cerebrum is absolutely and relatively larger than in any osseous or cyclostomous Fish.

2. Its heart approaches close to the condition of a low form of Reptile-heart; for its bulbus arteriosus is large and muscular; and it has rows of valves like those of the, so-called, Sauroid Fishes.

3. Its organs of reproduction are of a high organic grade; far higher than in any osseous Fishes. In one sex it has distinct and compact testes, vesiculæ seminales, and claspers. In the other sex, the oviduct is distinct from the ovarium; and it has the morsus diaboli, as well as the nidamental gland.

4. Its jaws are terminal, and its teeth, being fitted both for prehension and mastication, are superior to those of ordinary Plagiostomes.

5. The above characters are taken, almost word for word, from Professor Owen; and to them we may add, the position of the fins, which put the whole skeleton in symmetry with that of a Reptile or a Mammal. This last point is well urged by Mr. Hugh Miller, Footprints of the Creator, p. 153, and p. 160, &c.

6. Not to dwell exclusively on the Cestracion, we may assert generally, that all the higher forms of cartilaginous Fishes (Sharks, &c.) have a very high organic grade in their Class, determined collectively from their brain and nervous system, their heart and arterial system, from their organs of reproduction, from their whole economy of gestation and parturition, and from their functions during life.

7. Again, not dwelling exclusively on the Cestracion, we may add, "that the highest forms of cartilaginous Fishes are brought into connexion with Amphibious Reptiles by the existence of temporary gills, which disappear while these Fishes are in an early embryo state. These temporary gills, similar in function to the temporary respiratory tufts of certain Amphibious Reptiles (e. g. Frog and Salamander), seem (together with other points of analogy) to connect the cartilaginous Fishes with the Amphibia. They are seen in the Squalus and Raia, in the Pristis and Torpedo,

all of which are ovoviviparous; and (regarding these gills teleologically) they seem to be for the purpose of respiration while the creature is surrounded by the gelatinous fluid of the oviduct." (Note by Dr. Clark).

On the whole then,-taking for our guide the brain, the heart, the organs of reproduction, the symmetry of the whole skeleton, the locomotive power, and the despotic office of the higher cartilaginous Fishes in the economy of nature, —we are compelled to place them on the very summit of their Class. At one end of the scale of cartilaginous Fishes are certain species (such as the Cyclostomes) which descend lower than any hard-boned Fishes: but at the other end of the scale, the cartilaginous type ascends higher, beyond comparison, than any hard-boned species of the whole Ichthyic Class and if, on the development theory, a transition is to be made from Fishes to Reptiles, it must be made through the higher cartilaginous Fishes. But the chronological history of the Class entirely stultifies the theory of development; by proving, on the evidence of geology, that the very highest types were called into being first, while Fishes were the despots of creation; and that, afterwards, they not merely lost their place at the head of organic creation, but that the collective Class, so far as it was increased by the accession of new Orders and Genera, was developed on a degraded pattern.

Against this conclusion it has been argued, that most of the high cartilaginous Fishes are plagiostomous. True! and this embryonic character may be one mark of inferiority among Fishes on the same line of ascent, and nearly on the same grade. It might, for example, be one reason for putting a common Shark below a Cestracion. But it offers by itself no proof of inferiority, when Fishes far apart, and on a different line of ascent, are compared together; and their organic grade determined by such collective characters as are above enumerated. Embryonic development may suggest, or confirm, some good principles of classification ;-it