THEODOR BOVERI (1862-1915)

Theodor Boveri was born in Bamberg, Germany, the son of a doctor. Boveri was artistically inclined. He initially enrolled to study the humanities, but in 1881, Boveri entered the University of Munich to study anatomy and biology. He graduated with his doctorate - summa cum laude - in 1885, with the thesis, Beiträge zur Kenntnis der Nervenfasern (On the Study of Nerve Fibers). He received a scholarship, and was able to continue doing independent research at the zoology department in Munich.

In the late 1880's and early 1890's, Boveri published some of his most significant findings. Oskar Hertwig had already discovered that sperm and egg nuclei fuse during fertilization. Boveri studied the maturation of egg cells of Ascaris megalocephala, the horse nematode. He saw that as egg cells matured, there comes a point where chromosome numbers are reduced in half. Boveri was one of the first to see evidence of the process of meiosis.

Boveri was also one of the first to do experiments in the field of cytology. He chronicled the development of sea urchin eggs, when one egg was fertilized by two sperm. He concluded that male sperm nuclei and female egg nuclei were equivalent in the amount of hereditary information. They each had a half set (haploid number) of chromosomes. As long as there was a set of both (diploid number of chromosomes), there was fairly normal development of the sea urchin larvae. Any more or any less and there was abnormal development. When Mendel's laws were rediscovered in 1900, Boveri recognized the correlation between Mendel's factors and the cytology work being done on chromosomes.

In 1893, Boveri was appointed Professor of Zoology and Comparative Anatomy at the University of Würzburg. In 1902 and 1908, Nettie Stevens spent time in Boveri's lab, and likely was influenced by his cytology work. Boveri was not overly fond of Stevens, and complained about how she was a "bloodsucker," learning much but contributing little.

Boveri remained at the University of Würzburg until his death in 1915.

WALTER STANBOROUGH SUTTON (1877-1916)

Walter Sutton was born in Kansas City, and graduated from Kansas University. He was E. B. Wilson's graduate student in the Department of Zoology at Columbia University. In the spring of 1902, when he was only 25, Sutton deduced that chromosomes are the basis of heredity, and that the reduction of chromosomes in meiosis is directly related to Mendel's laws of inheritance.

The behavior of chromosomes and its importance in heredity was a "hot topic" at the turn of the century. Many scientists, including Sutton's supervisor, E. B. Wilson, were working on this problem. Theodor Boveri made the connection between chromosomes and heredity by doing his own observations and experiments. Sutton, working independently in Wilson's lab, came to the same conclusions. Wilson admitted later that when Sutton first explained his theory to him, he "did not at once fully comprehend his conception or realize its entire weight."

Sutton did his observations using grasshopper cells. His paper, in 1902, clearly showed that each chromosome is different, and meiosis reduces chromosome number in the gametes. Sutton's 1903 paper, The Chromosomes in Heredity, summarized and discussed the importance of his conclusions. The paper even more strongly drew the connection between Mendel's laws of heredity and chromosomes.

Wilson was very impressed with Sutton's abilities as an investigator. Unfortunately, Sutton never finished his doctorate. Sutton left research and entered medical school. He graduated from the College of Physicians and Surgeons at New York, and became a surgeon. Sutton served in France during World War I, and distinguished himself in treatments of wounded soldiers. Sutton died following an operation for appendicitis. He was only 39.

Links

The Biology Project at the University of Arizona

This site is a good resource in all areas of biology. It has a tutorial on meiosis.

UrchiNet Database

This site is an online database of information about sea urchins. It has a simulator that models early development of sea urchin in 3-D.

• Moore, John, A., 1985, Science as a Way of Knowing, American Society of Zoologists.

• Portugal, Franklin, H., and Cohen, Jack, S., 1977, A Century of DNA: A History of the Structure and Function of the Genetic Substance, The Massachusetts Institute of Technology, U. S. A.

• Stubbe, Hans, 1972 (English Translation), History of Genetics, The Massachusetts Institute of Technology, Cambridge, Massachusetts.

• Sturtevant, A. H., 1965, A History of Genetics, Harper & Row, Publishers, New York.