294 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1941 



wonderland of new knowledge, although as yet we have only crossed 

 the threshold. 



If justice is done, there will some day be monuments all over the 

 world to the banana fly. This tiny, light-colored insect has great 

 advantages in the genetics laboratory. It thrives in captivity, pro- 

 duces one generation in only 12 days, and each female may have 

 several hundred young; thus 2 years of the banana fly are equal 

 to 2,000 years of mankind. Its unique giant salivary chromosomes 

 seem almost made to order for the research of the scientists. 



One of the first things to impress a layman about the new knowl- 

 edge of the geneticists is the similarity of the life principle in plants 

 and animals. In the great genetics laboratory of the Carnegie In- 

 stitution at Cold Spring Harbor, Long Island, the other day I saw a 

 chart of the genes and chromosomes of the jimsom weed, a favorite 

 plant for colchicine experiments. Only across the hall was a similar 

 chart for the banana fly. While there were of course differences, 

 the similarities were even more apparent. In both cases, the living 

 matter consists of cells. In both cases each of these cells contains 

 a nucleus equipped with a definite number of chromosomes. In 

 both cases these chromosomes are filled with genes. In both cases, 

 each gene or group of them supplies a definite characteristic to the 

 living organism. It is not too much to say that from the stand- 

 point of science plants are only stationary animals, or that animals 

 are perambulating plants. 



In order to understand the startling new information which science 

 has unearthed regarding all living things, with its searching impli- 

 cations for our own social conduct, it is necessary to describe briefly 

 the mechanism of birth and growth, as the scientists now understand 

 it. For the sake of simplicity, I shall use the human body as my 

 illustration, although the process is similar throughout all organic 

 matter. 



The body consists of microscopically small cells, each containing 

 in its nucleus 48 chromosomes that are very much smaller still. 

 Twenty-four of these are contributed by the father and an equal 

 number by the mother. (This rule holds good throughout the world 

 of plants and animals, although the number of chromosomes differs 

 with each species.) The microscopic chromosomes contain the genes 

 and these have the clue to the very riddle of life itself. They are 

 known to control the growth and development of so many character- 

 istics that geneticists believe they probably dictate all growth proc- 

 esses. How many different genes there are in a human being no one 

 knows; it is believed that Drosophila has about three thousand. 

 Man probably possesses at least as many. 



