"Is there a unity of plan? The plan is the relative location of the parts. One can conceive very well the unity of plan without the unity of number; for it is sufficient that all the parts, whatever their number may be, keep always relatively to each other the same place. But can one say that the vertebrate animal, whose nervous system is placed above the digestive canal, is fashioned after the same plan as the mollusk, whose digestive canal is placed above the nervous system? Can one say that the crustacean, whose heart is placed above the spinal marrow, is fashioned after the same pattern as the vertebrate, whose spinal marrow is placed above the heart? Is the relative location of the parts maintained? On the contrary, is it not overthrown? And if there is a change in the location of parts, how is there a unity of plan?"
Müller draws nearer to the consideration of the development of the human embryo, and forcibly illustrates the falsehood of the pretended theory. "It is not long since it was held with great seriousness that the human foetus, before reaching its perfect state, travels successively though the different degrees of development which are permanent during the whole life of animals of inferior classes. That hypothesis has not the least foundation, as Baer has shown. The human embryo never resembles a radiate, or an insect, or a mollusk, or a worm. The plan of formation of those animals is quite different from that of the vertebrate. Man then might at most resemble these last, since he himself is a vertebrate, and his organization is fashioned after the common type of this great division of the animal kingdom. But he does not even resemble at one time a fish, at another a reptile, a bird, etc. The analogy is no greater between him and a reptile or a bird, than it is between all vertebrate animals. During the first stages of their formation, all the embryos of vertebrate animals present merely the simplest and most general delineations of the type of a vertebrate; hence it is that they resemble each other so much as to render it very difficult to distinguish them. The fish, the reptile, the bird, the mammal, and man are at first the simplest expression of a type common to all; but in proportion as they grow, the general resemblance becomes fainter and fainter, and their extremities, for instance, after being alike for a certain time, assume the characters of wings, of hands, of feet, etc."
Mr. Milne-Edwards takes the same view of embryonic generation:
"I agree with Geoffrey Saint Hilaire, that often a great analogy is observed between the final state of certain parts of the bodies of some inferior animals, and the embryonic state of the same parts of other animals belonging to the same type the organism of which is further developed, and with the same philosopher, I call the cause of the state of permanent inferiority arrests of development. But I am far from thinking with some of his disciples that the embryo of man or of mammals exhibits in its different degrees of formation the species of the less perfect of animate creation. No! a [{76}] mollusk or an anhelid is not the embryo of a mammal, arrested in its organic development, any more than the mammal is a kind of fish perfected. Each animal carries within itself, from the very origin, the beginning of its specific individuality, and the development of its organism, in conformity to the general outline of the plan of structure proper to its species, is always a condition of its existence. There is never a complete likeness between an adult animal and the embryo of another, between one of its organs and the transitory state of the same in the course of formation; and the multiplicity of the products of creation could never be explained by a similar transmutation of species. We shall see hereafter, that in every zoological group composed of animals which seem to be derived from a common fundamental type, the different species do not exhibit at first any marked difference, but soon begin to be marked by various particularities of constructure always growing and numerous. Thus each species acquires a character of its own, which distinguishes it from all others in the way of development, and each of its organs becomes different from the analogous part of every other embryo. But the changes which the organs and the whole being undergo after they have deviated from the common genesiac form, are generally speaking the less considerable in proportion as the animal is destined to receive a less perfect organism, and consequently they retain a kind of resemblance to those transitory forms."
Reason then and experience, theory and fact, philosophy and physiology, agree in protesting against the arbitrary doctrine of the unity of type in the animal kingdom; a doctrine which has its origin in an absence of sound scientific notions and a superficial observation of the phenomena of nature. Through the former defect men failed to consider that if the end of each animal species is different, different also must be its being, and therefore a different type must preside as a rule and supreme law over the formation of the being. By the latter, some very slight and partial analogies have been mistaken for identity and universality, and mere appearances have been assumed as realities.
From Blackwood's Magazine.
DOMINE, QUO VADIS? [Footnote 6]
BY P. S. WORSLEY.
[Footnote 6: See Mrs. Jameson's "Sacred and Legendary Art," p. 180.]
There stands in the old Appian Way,
Two miles without the Roman wall,
A little ancient church, and grey:
Long may it moulder not nor fall!
There hangs a legend on the name
One reverential thought may claim.
'Tis written of that fiery time,
When all the angered evil powers
Leagued against Christ for wrath and crime,
How Peter left the accursed towers,
Passing from out the guilty street,
And shook the red dust from his feet.
[{77}]
Sole pilgrim else in that lone road,
Suddenly he was 'ware of one
Who toiled beneath a weary load,
Bare-headed, in the heating sun,
Pale with long watches, and forespent
With harm and evil accident.
Under a cross his weak limbs bow,
Scarcely his sinking strength avails.
A crown of thorns is on his brow,
And in his hands the print of nails.
So friendless and alone in shame,
One like the Man of Sorrows came.
Read in her eyes who gave thee birth
That loving, tender, sad rebuke;
Then learn no mother on this earth,
How dear soever, shaped a look
So sweet, so sad, so pure as now
Came from beneath that holy brow.
And deeply Peter's heart it pierced;
Once had he seen that look before;
And even now, as at the first,
It touched, it smote him to the core.
Bowing his head, no word save three
He spoke—"Quo vadis, Domine?"
Then, as he looked up from the ground,
His Saviour made him answer due—
"My son, to Rome I go, thorn-crowned,
There to be crucified anew;
Since he to whom I gave my sheep
Leaves them for other men to keep."
Then the saint's eyes grew dim with tears.
He knelt, his Master's feet to kiss—
"I vexed my heart with faithless fears;
Pardon thy servant, Lord, for this."
Then rising up—but none was there—
No voice, no sound, in earth or air.
Straightway his footsteps he retraced,
As one who hath a work to do.
Back through the gates he passed with haste,
Silent, alone and full in view;
And lay forsaken, save of One,
In dungeon deep ere set of sun.
[{78}]
Then he who once, apart from ill,
Nor taught the depth of human tears,
Girded himself and walked at will,
As one rejoicing in the years,
Girded of others, scorned and slain,
Passed heavenward through the gates of pain.
If any bear a heart within,
Well may these walls be more than stone,
And breathe of peace and pardoned sin
To him who grieveth all alone.
Return, faint heart, and strive thy strife;
Fight, conquer, grasp the crown of life.