MYSTERIES OF GROWTH.

Greymouth Evening Star, 17 February 1930, Page 7

MYSTERIES OF GROWTH.

TOLD BY THE TADPOLE. A few tadpoles, by refusing to grow into frogs, have played an important part; in helping scientists to discover Ih<( secrets of grow'th mental and bodily—in man. To medical men ol the past tlieie appeared no reason why one individual should grow into a giant and another a. dwarf; one a. genius, another a half-wit; one a perfect physical man. another a freak. They were aware of the existence of two tiny organs—the thyroid gland and the pituitary gland—but it never occurred to them that these were regulating factors of vital importance. At last these glands have yielded up their secrets. The pituitary gland in man is protected by a bony chamber in the centre of the skull. It is smaller than a. grape. The thyroid gland, which is a little larger, is situated near the base of the neck. Despite their insignificant size, these two glands supply to the brain, the tissues, and the bones certain chemical substances which are essential to their growth and development. Any abnormality in the two glands produces corresponding abnormality in growth. Investigators decided to remove the tadpoles’ thyroid glands, in order to ascertain whether their absence would have any physical effects. The operations were carried out with the utmost care and with the most delicate instruments, for the glands were merely liny specks in the tiny bodies of their owners, and it was necessary that no important organs should be injured. The thyroidless tadpoles never grew into frogs. They grew legs, but they did not discard their tails, and so remained in an intermediate state. 'Phis proved that the thyroid gland lias a, definite connection with the process of normal growth. What, did it supply to the body which, was so essential to full and mature development? That question was answered by further experiments. Tadpoles from whicu the thyroid glands have been removed -were given food impregnated with various chemical substances, and one of these was iodine. When iodine-laden food was put on the tadpoles’ menu they grew into mature frogs just as they would had they retained their thyroid glands. But when iodine-laden food was discontinued they became sickly, development ceased, and deformities occurred. lodine, then, was the essential substance the thyroid gland supplied. This led to a line of investigation which showed that the* thyroid gland performed similar functions in the human body.

Goitre, a prevalent complaint, had defied satisfactory explanation or treatment. It is now known to result from the failure of the thyroid gland adequately to discharge its functions. Medical men have found iodine of great value in treating ailments traceable to this gland. In one district on the West Coast of Ireland the inhabitants are conspicuously well-developed and healthy. This has been traced to the local children’s habit of eating an edible seaweed which is rich in iodine. In othei 1 parts of the country, where goitre is common, analysis of the drinking-water has shown that iodine is either absent altogether, or present in only very small quantities. The pituitary gland has a stimulating and regulating influence on the formation of bone. It accomplishes its work by producing certain chemical substances called hormones, which are passed into the blood stream and carried to every part of the body. If the pituitary gland fails in its duty the bones do not harden, the general growth of the body is retarded, ami dwarfism results. But if the. gland is abnormally active, giantism results. A multitude of abnormal conditions has been ascribed to glandular malformation, among them arrested growth, criminal tendencies, idocy and even obesity. It is possible that, in the not very distant future, surgeons may be able, by administering gland-stimulants, or by operations on the glands, to change not only the appearance but also the characters of their patients—to transform weakness into strength, repulsiveness into beauty, and stupidity into intelligence.