ARE PARASITES DESIGNED?

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one of these, when carried into other parts of the body, arise certain partially-developed forms which cause disorganization more or less extensive in the brain, the lungs, the liver, the heart, the eye, &c.; often ending fatally after long-continued 'suffering. Altogether, the parasites of the human body, internal and external, animal and vegetal, number two or three dozen species; besides which almost every known animal has its peculiar species, generally more than one, and sometimes as many as man, or even more. Can we say that parasites were purposely endowed with constitutions. fitting them to live by absorbing the juices of the human body; that they were designedly furnished with appliances, often of a formidable kind, enabling them to root themselves in and upon the body; and that they were made prolific in an almost incredible degree in order that their germs might have a sufficient number of chances of finding their way into the human organism? “Shall we say that man,' the head and crown of things,' was provided as a habitat for these parasites? Or shall we say that these degraded creatures, incapable of thought or enjoyment, were created that they might cause unhappiness to man? One or other of these alternatives must be chosen by those who contend that every kind of organism was separately devised by the Creator. Which do they prefer? With the conception of two antagonistic powers, which severally work good and evil in the world, the facts are congruous enough. But with the conception of a supreme beneficence, this gratuitous infliction of misery on man, in common with all other terrestrial creatures capable of feeling, is absolutely incompatible."1

1 Spencer: Principles of Biology, i. 344. Büchner: Force and Matter, p. 95.

On the hypothesis of Special Creation this is a tremendous difficulty, and if the theory of Evolution did not clear it up it would leave us in no worse position than before. Mr Spencer endeavours to explain it by the principle of "incidental evil," which, in the nature of things, is connected with a process like that of evolution-evil which is but "a deduction from the average benefits," and is "ever being self-eliminated," the tendency being "to produce a type of superior organisms less liable to the invasions of the inferior." Thus, though there may arise the question, Why could they not have been avoided? there does not arise the question, Why were they deliberately inflicted? Whatever may be thought of them, it is clear that they do not imply gratuitous malevolence." This seems hardly enough for us, on the view maintained in this Essay; for in so far as the bodies of these creatures exhibit what we must call mechanism, we must hold them to have been designed. We confess to some difficulty. Dr Bree says, "We cannot answer these questions;" ."1 but unless they admit of an answer they seem to leave room for the denial of Design in any and every part of the animal or vegetal creation. Our first suggestion is, that since incidental evils are correlated with the process to which they are incidental, they do not carry with them any denial of design in that process; but, on the contrary, so far as they are fitted for any purpose, or seem to exhibit any design themselves, they prove design in the process of which they are the incidents; much as the complex character of the refuse from chemical works indicates complexity in the processes which gave rise to it, or as the regularity of blurred letters on a fragment of 1 Fallacies of Darwinism, p. 68.

PARASITES AND DISEASES.

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dirty paper speaks of the printing machinery through which it has accidentally passed. A second suggestion is, that parasites, in so far as they affect chiefly individuals of uncleanly habits or careless feeding, and kill those whose organs are weakest, are engaged in a useful work, on the principle of Natural Selection, and may have been as much designed for that purpose as the general struggle for existence is designed. A third suggestion I find in Mr J. J. Murphy's work— viz., that parasites are descended from species which were not parasitic, and have become self-adapted to new habitats, so that we have in their existence only a particular case of the question why pain and disease are permitted at all.1 If either of these suggestions should prove accordant with fact, it will probably supply at the same time a solution to the class of difficulties referred to by Mr Darwin in the following passage:-Finally, it may not be a logical deduction, but to my imagination it is far more satisfactory to look at such instincts as the young cuckoo ejecting its foster-brothers, ants making slaves, the larvae of ichneumonidæ feeding within the live bodies of caterpillars-not as specially endowed or created instincts, but as small consequences of one general law, leading to the advancement of all organic beings, namely, multiply, vary, let the strongest live and the weakest die.2

Diseases other than parasitic seem to admit of an easier explanation. That certain substances should be so related to the blood that they will "poison" it if introduced, may be as inevitable as that pointed weapons should be fitted to pierce the skin, or that plane surfaces should admit of contact throughout their extent 1 Habit and Intelligence, chap. xxvii. 2 Origin of Species: Instinct.

while a cube and a sphere can only touch at one point. There is some truth in Professor Huxley's strong statement that plague, pestilence, and famine are admitted by all but fools to be the natural result of causes for the most part fully within human control, and not the unavoidable tortures inflicted by wrathful Omnipotence upon His helpless handiwork. No doubt there are diseases which no human prudence can at present guard against, and no human skill can cure; and if one has lost a wife through cancer, or a son through consumption, he may find it difficult for the moment to believe in the Divine beneficence; but the morbid growth of cancer may be as inevitable under some circumstances as the accumulation of slag at a foundry, or the flooding of a low country after heavy rains. Dr Carpenter leans to a belief that cancer results from a poison in the blood; 2 and Mr Murphy suggests that it may be a portion of the organism which has got away from the control of the general life, and leads a life of its own, parasitic on the rest 3in either of which cases we have only the difficulty which we have just endeavoured to remove. When we have traced back all diseases to their causes, we may be able to divert their currents from touching us-as people dig a hole in the hardening side of a lava stream to turn away the flow which threatened the destruction of their village. In the meantime we suffer through our ignorance: but Natural Selection may do as much good by preserving only those who are wise in soul, as by caring for those who are strong in body; and it is certain that since man's mind became at all highly developed, it is mental variations which are most selected.

1 Lay Sermons, p. 283.

2 Human Physiology, p. 371.

2 Habit and Intelligence, chap. xxvii.

PAIN NOT AN EVIL.

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The Existence of Pain.-Admitting that liability to disease and injury was inevitable, it may still be asked, Why they should be accompanied by pain? Cancer, stone, and every other dreadful complaint might be submitted to, but for the excruciating agony. Let us look at this. Pain per se is an evil; but allowing for that conditional necessity in nature which renders it impossible to effect all imaginable unmixed good at a bound, it can easily be shown that the suppression of the sense of pain would imply the extinction of the highest forms of life. We have seen that the higher animals, such as man, have the most highly differentiated organization, and can least afford to have a part of the body cut off, or any organ severely injured. It is trite to say that in the e very animals the nervous system is the most highly developed, and the capacity for pain the greatest. It may be a newer thought that, since this capacity increases from lowly organisms up to man, it must have been developed by Natural Selection; and that taking this fact in connexion with Mr Darwin's well-proved rule that Natural Selection never produces in a being anything injurious to itself, but acts solely by and for the good of each, we are supplied with a proof that pain is a beneficent thing. Darwin, in passing, expresses his agreement with Paley, that no organ is formed for the purpose of causing pain, or for doing an injury to its possessor; but the higher animals are so sensitive to pain that one almost expects to find in the Origin of Species a chapter on the uses of this sensitiveness in the struggle for life, and on its development by the aid of Natural Selection. It is quite evident that an animal body, in its very nature, admits of being injured and disorganized 1 Origin of Species, chapter vi.