A semi-legendary plant in Colombia is the ayahuasco or dead man’s vine. From it Indians make a brew which, it is claimed, is quite similar to the imaginary drug by which Dr. Jekyll split the good and evil elements of his character. When a medicine man first gulps the brew—this is an ethnological report which the botanists cannot confirm—he turns deadly pale, trembles in every limb, and the expression on his face is one of intense pain and horror. This is followed in about a minute by a reckless fury in which he seizes whatever lies at hand and starts beating the trees and ground. In about ten minutes the excitement leaves him and he falls to the earth, completely exhausted. There are not as yet any scientific accounts of the plant’s influence.
The Insect With Fourteen Lives
A pinhead-sized wormlike larva of a louse may possess one of life’s ultimate secrets—an elixir of controlled growth.
The strange ways of life of hormophis hamamelidid—which goes through fourteen different life stages in the course of a year’s lifetime—are being studied by scientists in the hope of isolating a mysterious something which may open the door of some of the greatest paradoxes of biology.
The insect is an aphis which causes galls, growths comparable to animal cancers, on witch hazel leaves. These growths result when the aphis injects into the leaf by means of a microscopic apparatus like a hypodermic needle an infinitesimally minute amount of an unidentified substance. The gall grows around and over the insect. It becomes the tiny creature’s home.
The substance completely changes the nature of the plant cells. They normally would become leaf cells, highly specialized to fit into leaf growth. Now they become gall cells. Something similar happens in cancer, except that the new cell growth, having escaped from the government of the animal body, is entirely uncontrolled. The gall cells, however, still remain under some sort of control. They always form galls and they do not kill the leaf, which is necessary for their existence.
Marvelous is the life story of the aphis itself. The sequence starts with a “stem mother”, a newly hatched female. She injects the substance into the leaf and the house builds itself around her. Inside this house she passes through four stages. Her structure changes completely four times. That is, she becomes in a sense four different animals, one after another. In the fourth stage she gives birth to from fifty to a hundred living young.
Each of these young, in turn, goes through four stages. In the last of these they have wings. The winged insects crawl out through a hole in the bottom of the gall. Each produces from ten to twenty young on the bottom of the leaf. Each of the young, in turn, goes through five stages. During the last they are both males and females. This is the only time the male makes its appearance in the life cycle. All the other births are by parthogenesis.
Each of the females lays eggs in the winter on the witch hazel. The buds are destined to become leaves in the early Spring. The eggs hatch a few days before the leaves appear. Each of the newly hatched aphids—all females—injects some of the house-building material into the leaf upon which she finds herself. She becomes a new “stem mother” and the strange process starts all over again.
The rapid reproduction rate might well be overwhelming to the witch hazels, and consequently suicidal for the insects, except for certain enemies which keep down the numbers of the “lice”. Such tiny forms of life as larval lacewings are able to crawl through the hole in the bottom of the gall and feed on the occupants during their various stages.