Science Siftings

New Zealand Tablet, Volume XLIV, Issue 1, 4 January 1917, Page 45

Science Siftings

By 'Volt.'

The Best ; Foods/

■ Not only is there no 'best ; food,' but in the very nature of things- there cannot be. ; , : No single food yet" discovered will alone sustain human beings in perfect health and vigor for any' considerable period. On the other hand, food ever yet invented by the wit of man or resorted to under the bitter necessity but what has certain,"' may ■'-. be very '- : modest, virtues and uses of its .own. The utmost that can be said in the way of generalisation is that certain great food-staples have proved themselves within the age-long experience of humanity to possess a larger amount of nutritive value, digestibility, and other beneficial qualities, - and a smaller proportion of' undesirable properties, than any other. -. These, through an exceedingly and gradual nrocess of the survival of the fittest, have come to form the staples of food in common use by the human race-all over the world. It is really astonishing how comparatively' few of them there are when we come to consider them broadly the flesh and milk of three or four domesticated-animals; flesh of three or four and eggs of one species of domesticated birds three great grains— rice, and maize— a half dozen smaller and much less frequent ones ; 100 or so species of fishes and shell fish ; two sugars ; a dozen or so starchcontaining roots and tubers, only two of which—the potato and the manioc of real international importance; 20 or 30 fruits ; 40 or 50 vegetables—these make up two-thirds of the food supply of the inhabitants of 1 the world. "■■"■_ ..' ' The Stinging Nettle. The stinging nettle was put to many uses in medieval times. Its fibre before the days of cheap cotton used to be spun and woven into a wide variety of materials from stout rope to fine lace, and good paper has been manufactured from it. Then, too, it was used medicinally ; but what herb was not ? The word nettle is said to be derived from needle, and refers to the sharp hairs. Though firm enough to pierce the skin, they are hollow and brittle, and break off in it, exuding a poison. Under a high-powered microscope the hollow nettle hair is seen to be partly occupied by living protoplasm—a transparent, viscid substance, which shows an active streaming movement, and has embedded in it a dense kernel or nucleusa living ' cell,' or life unit. The space" in the cell not occupied by protoplasm is filled with clear liquid, which contains the poison. This has been examined chemically by using a large quantity of nettle hairs, and is found to contain formic acid—the same irritating acid which is secreted by ants when they sting. The juice contains also a special poison in minute quantities, an albuminous substance, which resembles that of the poison-sacs at the base of the teeth of snakes. Besides the common nettle, there are the small nettle (Urtica minor) and the Roman nettle (U. pilulifera), which is not considered indigenous to Britain; it is found in the east of England, chiefly near the sea, and is the most virulent of the three. Bullet-Proof Caps. . The steep caps which are being used by our soldiers at the front are marvels of lightness and strength.

- -" ~> -" -" -_ N '■ - ■.. -v : ,„ *-/ ; 'o " They are made of manganese "steel and are bullet-proof f to a Webley i automatic pistol :- at ■ five; yards; % Further- '<'■ more, during a recent experiment, one of the caps, was only slightly dented when a heavy poker, raised over the head and brought down 'with both hands and all possible force, was crashed : upon it. The British helmets[: are ; called ;S soup .plates' by the soldiers* and are so constructed that ; they not • only * protect the!; wearer .' from the enemy's weapons but from , fragments of the cap itself. Rubber studs are: placed between the helmet and: the skull, awhile next to the latter is a double lining, of wadding and felt. This not only renders the helmet more comfortable, helps "to protect the skull ' from jagged fragments: . . ' : ' : 7-'. ~ • ■ / /f';