Reproduction, Rings, Rivers

Science, medicine, education, social study, the arts, the humanities, Herbert Hoover and Franklin Roosevelt took their turns on the stage last week in Philadelphia as the University of Pennsylvania celebrated its 200th birthday (see p. 43). High lights in science:

"Couples in a Dance." Well known to every first-year biology student, the paramecium is a one-celled, slipper-shaped little animal which lives in ponds and puddles. In the one-celled kingdom the paramecium is a giant, just visible to a good, sharp, naked eye. For three years Dr. Herbert Spencer Jennings, distinguished University of California at Los Angeles zoologist,* has been watching a thousand generations of one species, Paramecium bur-saria, under his microscope. Last week he told about his paramecia's mating habits.

Paramecia reproduce mostly by fission --splitting in two--like the smaller and simpler amoebae, but now & then paramecia mate by clinging together in pairs. This seems to put new vigor into the reproductive cycle. Some paramecium pairs come together violently, adhere for 24 to 36 hours. Other matings are gentler, even flirtatious. Dr. Jennings said he had seen pairs nuzzle each other several times, then swim off side by side in graceful spirals, like "couples in a dance." After years of watching these goings-on, Dr. Jennings was willing to carry the origins of social behavior all the way back to one-celled animals.

Tree Rings. Dr. Andrew Ellicott Douglass, University of Arizona astronomer, is the founder of the 20th-century science of "dendrochronology"--telling time (in years) by means of tree rings. The thickness of the annual growth rings in trees is proportional to the year's rainfall. Thus the rings fall in patterns corresponding to the varying rainfall supplies during the life span of the tree. By matching patterns from logs of recent date to successively older & older specimens, Dr. Douglass carried a continuous record back several hundred years. Examining logs in the ruins of Indian pueblos built before Columbus, he was able to tell the exact year when the wood was cut.

Last week Dr. Douglass announced that his rainfall calendar had been carried back to the lifetime of Christ, specifically to the year 11 A.D.

Molengraaff River. Carved in the sea floor off the Hudson, Delaware and Congo Rivers are huge canyons whose beds lie 7,500 to 10,000 ft. below sea level. How were they formed? Possibly by ancient rivers, when the seas were far below their present level. Geologists know that during the Ice Age, which began to recede some 20,000 years ago, the ocean level was lower than it is now, because great masses of water were locked up in the land glaciers. But the continents could hardly have stored water masses tremendous enough to have raised the sea level from one and a half to two miles. A theory held by some geologists is that the drowned canyons were cut by the sapping action of springs oozing under the sea floor.

Geologist Roy Dickerson of Atlantic Refining Co. favors the sapping-spring theory, believes the Ice Age drainage to the sea was inconsiderable. Last week he described a great underground valley lying on the China Sea bottom between Borneo, Sumatra and the Asiatic mainland. In honor of its Dutch discoverer, it is called the Molengraaff River. Twenty thousand years ago, Borneo, Sumatra and Java were joined to the mainland; evidently at that time the Molengraaff was a real river, because it fits in with the drainage pattern of the lands which remain above water today. Its present bed is only a little more than 300 ft. under the sea level. So Dr. Dickerson concludes that the seas must have risen less than 300 ft. since the Ice Age.

* Dr. Jennings, 72, left the Johns Hopkins faculty two years ago when the Hopkins age rule forced him to retire. U.C.L.A. was glad to get him.

This file is automatically generated by a robot program, so reader's discretion is required.