"ONE MAN'S MEAT."

Waikato Times, Volume 103, Issue 17384, 21 April 1928, Page 10

"ONE MAN'S MEAT."

POISONOUS ANIMALS. WHY DO THEY KILL? This Dominion is extremely fortunate in being almost immune from anything in the nature of poisonous fauna, the katipo spider being the most notable of the very few harmful insects. Other countries have many such ills to guard against, from snakes to .beetles. No hard and fast line can be drawn between poisons and other substances. For there are many chemically diverse kinds of poisons, and even if we say that a poison is defined by its destructive or disintegrative effect when introduced into a living creature, we have to admit that one man's food may bo another man's poison, and that much depends on the dose. Many a powerful poison, such as strychnine, may be life-saving in a minute dose. An adder's venom will kill a rabbit, but the hedgehog is unaffected. The poisoning effect has two sides; it often varies with the physiological state of the assailant, or poisoning animal and also with the conditioner tho victim or poisoned animal. £kl may vary with the moon. A berry is poisonous to some and lobsters to others. The hornbill enjoys the seeds of nux vomica; and while swallowing one blisterbeetle would probably be fatal to a man, the scorpions can suck their juices with impunity. All living matter is made up of the nitrogenous carbon-compounds called proteins, such as the albumen of white of egg, or the casein of milk; yet each distinct type of animal has specific proteins, peculiar to itself. And these proteins, for some reason or other, are not good mixers. If the serum of the blood of a particular animal is introduced into the blood of another animal, even a related species it brings about a destruction of red blood corpuscles. The strange protein has a disintegrative influence, even on substances not very unlike itself. In other words, the strange protein acts as a poison.

Digestive Processes.

But as man is continually using various proteins as food, and experimenting with proteins that he never tried before, we have to recognise the value of those digestive processes that break down the proteins into their constituents called amino-acids. The smaller molecules that result from the breaking-down of larger ones are able to pass more readily through the wall of the food canal into the absorbing blood vessels, and that is a great gain; but another aspect of the process is that the edge is taken off the strange proteins. They are disarmed, as it were, more precisely, they become harmless by being broken up into their constituent amino-acids.

In a recently-published German book on "Poisonous Animals," Professor E. N. Pawlawsky, of Leningrad, has given an interesting grouping. First of all, there may be separated off those animals that have no special poisonous organs or glands, yet may prove their virulence if they are used as food, or if their blood, extracts, or exudations are introduced experimentally or non-aggressively into some other creature. This is a passive poisonousness, depending on some peculiarity in the chemical composition of the poisoner's tissues. It is well illustrated by most of the inflatable "Puffers" or "Globe-Fishes," by the "blister-beetles," whose blood is rich in the poison cantharidin, and by a number of parasites, such as threadworms, whose exudations have a poisoning effect.

Poison-Ejectors. All the other poisonous animals, extraordinarily diverse in nature, have this in common that they have specialised structures or organs for the preparation of the poison and its aggressive explusion into or on to a victim. Thus, to begin near the base of the genealogical tree, there are the jellyflshes and sea anemones and Portuguese men-of-war, whose skin contains myriads of stinging-cells. The ejection of miscroscopic lassoes liberates poisons, such as thalassin and congestion, which are often very virulent, as bathers sometimes discover. Besides discouraging the attacks of hostile animals, the stinging threads often serve to paralyse and capture the small organisms that are used as food. Another group may be defined to include a large number of insects that exude irritant blood aggressively from various strategic points on their body. The explusion is sometimes a gentle exudation, as in oil-beetles; but it may be energetic enough to deserve the name of squirting, as in the large caterpillar-like larvae of the birch saw-fly. Poisonous Weapons. The mostly highly-evolved animalpoisoners are those that possess not only poison-glands, but,some specialised arrangements for introducing the venom into a victim. Perhaps it might be useful to condone and even adopt the peculiar use of the word "sting" to denote any of these poisoning instruments, which are so diverse in nature. The spider "stings" with its first pair of mouth appendages, the scorpion with a sharp spine at the end of its tail; the duckmole stings with a spur, the weaver-Ash with a fin-ray; the procession of caterpillars and many others sting with their nettle-like hairs. How striking it is that a venomous snake should have evolved its poison-injection apparatus out of the tooth, while a bee's sting is a transmogrified egg-laying organ. Our human conception of the poisoner is emphatically sinister, but among animals the use of poison is as often protective as aggressive; and it may be in the service of love as well as of hunger. ,-___«