These pale faces, seamed and weary, seeking solace here, and peace,
Speak more eloquent a language than the olden seers of Greece;
More than Plato taught when round him stood the Athenians rapt and dumb;
More of wisdom than e'er echoed through the groves of Tusculum.
The poor lives and poor endeavors of these toilers of the sod
Teach life's grand and noble lessons—patience, faith, and trust in God;
And the weight of earth falls from me, for I hear a soft voice thrill,
And my heart lies down in quiet as it whispers, "Peace, be still!"
Constantina E. Brooks.
THE IMMUTABILITY OF THE SPECIES.[151]
III.
No alleged factor of evolution is so capable of arresting the attention of a physiologist as correlation of growth. To this law we have before often incidentally alluded. But as we conceive that it furnishes strong confirmation of our views, it behooves us to extend to it a somewhat more lengthy treatment.
The current impression is, that every authenticated instance of variation is so much added to the probabilities of the evolution of the species; and that the refutation of Darwinism is rendered difficult just in proportion to the number of proofs of variability. It is natural, then, that Darwin should accord prominence to those factors which play a part in inducing modification. Conspicuous among these factors is correlation, the nearest approximation to a law of all the colligations of facts involved in Darwinism.
Correlation is a bond, nexus, or connection subsisting between different growths. Owing to it, a modification seldom arises in any portion of the organism without involving a corresponding change in another part. It is often not a little difficult to determine which part first varies and induces the modification of the other. Frequently, characters simultaneously vary, and are apparently affected by some distinct cause. Correlation is an important subject for Darwin; for, owing to its operation, varieties seldom differ from each other by a single character alone. He declares that "all the parts of the organism are, to a certain extent, connected or correlated together," and that "of all the laws governing variability, that of correlation is the most important." Parts, however, differ greatly with respect to the strength of their connection. In some parts, the tie is ever manifesting itself; in others, it is seldom traceable. Each character, when developed, tends to stimulate the development of others. But, owing to adversity of conditions, or to being systematically suppressed by man, these correlated growths lose all ability to respond to this stimulus, and, in consequence, fail to develop.
We intended to adduce quite a number of facts from Darwin, in order to enable our readers clearly to understand the precise nature of correlation. But want of space forces us to change our mind. We do this with less reluctance, when we consider that those for whom this article is more especially written have already familiarized themselves with those facts.