Natural Law in the Spiritual World

by Henry Drummond

Observant visitors to the sea-side, or let us say to an aquarium, are familiar with those curious little creatures known as Hermit-crabs. The peculiarity of the Hermits is that they take up their abode in the cast-off shell of some other animal, not unusually the whelk; and here, like Diogenes in his tub, the creature lives a solitary, but by no means an inactive life.

The Pagurus, however, is not a parasite. And yet although in no sense of the word a parasite, this way of inhabiting throughout life a house built by another animal approaches so closely the parasitic habit, that we shall find it instructive as a preliminary illustration, to consider the effect of this free-house policy on the occupant. There is no doubt, to begin with, that, as has been already indicated, the habit is an acquired one. In its general anatomy the Hermit is essentially a crab. Now the crab is an animal which, from the nature of its environment, has to lead a somewhat rough and perilous life. Its days are spent among jagged rocks and boulders. Dashed about by every wave, attacked on every side by monsters of the deep, the crustacean has to protect itself by developing a strong and serviceable coat of mail.

How best to protect themselves has been the problem to which the whole crab family have addressed themselves; and, in considering the matter, the ancestors of the Hermit-crab hit on the happy device of re-utilizing the habitations of the molluscs which lay around them in plenty, well-built, and ready for immediate occupation. For generations and generations accordingly, the Hermit-crab has ceased to exercise itself upon questions of safety, and dwells in its little shell as proudly and securely as if its second-hand house were a fortress erected especially for its private use.

Wherein, then, has the Hermit suffered for this cheap, but real solution of a practical difficulty? Whether its laziness costs it any moral qualms, or whether its cleverness becomes to it a source of congratulation, we do not know; but judged from the appearance the animal makes under the searching gaze of the zoologist, its expedient is certainly not one to be commended. To the eye of Science its sin is written in the plainest characters on its very organization. It has suffered in its own anatomical structure just by as much as it has borrowed from an external source. Instead of being a perfect crustacean it has allowed certain important parts of its body to deteriorate. And several vital organs are partially or wholly atrophied.

Its sphere of life also is now seriously limited; and by a cheap expedient to secure safety, it has fatally lost its independence. It is plain from its anatomy that the Hermit-crab was not always a Hermit-crab. It was meant for higher things. Its ancestors doubtless were more or less perfect crustaceans, though what exact stage of development was reached before the hermit habit became fixed in the species we cannot tell. But from the moment the creature took to relying on an external source, it began to fall. It slowly lost in its own person all that it now draws from external aid.

As an important item in the day's work, namely, the securing of safety and shelter, was now guaranteed to it, one of the chief inducements to a life of high and vigilant effort was at the same time withdrawn. A number of functions, in fact, struck work. The whole of the parts, therefore, of the complex organism which ministered to these functions, from lack of exercise, or total disuse, became gradually feeble; and ultimately, by the stern law that an unused organ must suffer a slow but inevitable atrophy, the creature not only lost all power of motion in these parts, but lost the parts themselves, and otherwise sank into a relatively degenerate condition.

Every normal crustacean, on the other hand, has the abdominal region of the body covered by a thick chitinous shell. In the Hermits this is represented only by a thin and delicate membrane—of which the sorry figure the creature cuts when drawn from its foreign hiding-place is sufficient evidence. Any one who now examines further this half-naked and woe-begone object, will perceive also that the fourth and fifth pair of limbs are either so small and wasted as to be quite useless or altogether rudimentary; and, although certainly the additional development of the extremity of the tail into an organ for holding on to its extemporized retreat may be regarded as a slight compensation, it is clear from the whole structure of the animal that it has allowed itself to undergo severe Degeneration.

In dealing with the Hermit-crab, in short, we are dealing with a case of physiological backsliding. That the creature has lost anything by this process from a practical point of view is not now argued. It might fairly be shown, as already indicated, that its freedom is impaired by its cumbrous exoskeleton, and that, in contrast with other crabs, who lead a free and roving life, its independence generally is greatly limited. But from the physiological standpoint, there is no question that the Hermit tribe have neither discharged their responsibilities to Nature nor to themselves. If the end of life is merely to escape death, and serve themselves, possibly they have done well; but if it is to attain an ever increasing perfection, then are they backsliders indeed.

A zoologist's verdict would be that by this act they have forfeited to some extent their place in the animal scale. An animal is classed as a low or high according as it is adapted to less or more complex conditions of life. This is the true standpoint from which to judge all living organisms. Were perfection merely a matter of continual eating and drinking, the Amœba—the lowest known organism—might take rank with the highest, Man, for the one nourishes itself and saves its skin almost as completely as the other. But judged by the higher standard of Complexity, that is, by greater or lesser adaption to more or less complex conditions, the gulf between them is infinite.

We have now received a preliminary idea, although not from the study of a true parasite, of the essential principles involved in parasitism. And we may proceed to point out the correlative in the moral and spiritual spheres. We confine ourselves for the present to one point. The difference between the Hermit-crab and a true parasite is, that the former has acquired a semi-parasitic habit only with reference to safety. It may be that the Hermit devours as a preliminary the accommodating mollusc whose tenement it covets; but it would become a real parasite only on the supposition that the whelk was of such size as to keep providing for it throughout life, and that the external and internal organs of the crab should disappear, while it lived henceforth, by simple imbibition, upon the elaborated juices of its host. All the mollusc provides, however, for the crustacean in this instance is safety, and, accordingly in the meantime we limit our application to this. The true parasite presents us with an organism so much more degraded in all its parts, that its lessons may well be reserved until we have paved the way to understand the deeper bearings of the subject.