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Nettie Maria Stevens was born on 7th July in the year 1861 in the small town of Cavendish, Vermont and died in in Baltimore (Maryland) on May 4th in the year 1912 due to Breast cancer. Fundamentally she was known as an early American geneticist.

Her father was a carpenter due to which he had to work hard to give his children a better education but Nettie Maria Stevens was always a prominent and outstanding student of her time, beside this she was also famous for having a special capability by being good in science and mathematics.

She completed her high school at the age where girls never reach that level of education, but due to the fact that she belonged to a poor family she had to work hard to meet her requirements and avail every possible opportunity as well. She worked as a school teacher as well as a librarian.

In 1899 Nettie Maria Stevens received her Bachelors degrees in Art furthermore; in the year 1896 she entered in Stanford University in California, from where Stevens received her master’s degree in year 1900. She completed her postgraduate work from Bryn Mawr College.

In Bryn Mawr College she worked under numerous well-known staff members of the college like Thomas Hunt Morgan as well as Edmund Wilson who assisted her by preparing the way for her later contributions to science.

After her arrival from United States in the year 1904, Nettie Maria Stevens initiated her original research, at that time Carnegie Institute allowed her to do so. She presented many theories, their applications as well as experiments to prove her work and statements as well. Her contribution in this field is still praised and followed by others as well.

Marilyn Bailey Ogilvie one of the well known authors wrote in her famous book   Women in Science that “yet beyond these accomplishments passed along her expertise to a new generation illustrating the importance of the women’s colleges in the education of women scientists.” (Marilyn Bailey Ogilvie, 1991)

Nettie Maria Stevens worked so much in the field of science that still her name and work is remembered and praised. Besides her theories, and researches the most prominent work due to which she is remembered is her work on the chromosomal determination of sex. This point was initially raised in her paper, which was published by her in year 1905, which was declared as “Studies in Spermatogenesis, with Especial Reference to the Accessory Chromosome.” (Marilyn Bailey and Clifford J. Choquette, 1991)

Nettie Maria Stevens and Wilson statements regarding this suggests that “sex was determined by a single difference between two classes of sperm-the presence or absence of an X chromosome” (Nancy Woloch, 2001) but still this point was not understood and clear to her completely. She finished her PhD in morphology in 1903 as T. H. Morgan’s student. He did not agree with the above mentioned statement as according to him there were two classes of sperm.

Nettie Maria Stevens made numerous researches, experiments and Studied Tenebrio molitor beetles as well. Furthermore she found out that unfertilized eggs in female beetles always contain an X chromosome. The male beetle’s sperm will always enclose either an X or a Y chromosome.

According to her research it was illustrated that female beetles are the                           reason of eggs fertilization by the sperm that carries X chromosome, not only this but it was also illustrated that by grouping egg and Y-chromosome, sperm will produce in male beetles.

She illustrates the fact that female cells contains almost 20 chromosomes, but if we compare this with men’s than there is a bit of a difference in them as male cells almost contains 19 large chromosomes, besides these 19 chromosomes they have one small chromosomes as well. With her researches she proved that the X body paired with a 20th, much smaller, is chromosome in meiosis.

By further exploring her thoughts and researches she found out the fact that there is a perfect correlation between sex and chromosome type. Females will always carry two X chromosomes, as well as an egg that will be fertilized in a manner that when sperm carries the males X chromosomes then this will always produce a female, similarly if it will be fertilized in a way that it will carry a male’s Y chromosome than it will produce a male.

According to 1901’s MBL report Nettie Maria Stevens was an undergraduate student. In the year 1905 this report was generated again and she was mentioned as a graduate student and this was the point were Stevens’s works, theories, researches were published as well on May 23 in year 1905. Furthermore she also conducted her researches in zoology as well with a well-known scientist of her time T. H. Morgan.

Beside her contributions in this field Edmund Beecher Wilson who is fundamentally a biologist from Columbia University in New York City, also worked on these issues and gave his statements and discoveries as well. They both established the same concluding points but later it was rectified that Nettie Stevens was not praised and credited well for her theories, work, researches as well as experiments.

Beside this fact that she was a well- known and famous American geneticist some others got her credit by neglecting her contributions. But in year 1912 after her death she and her work gained notoriety from Thomas Hunt Morgan’s his statement that “Modern cytological work involves an intricacy of detail, the significance of which can be appreciated by the specialist alone; but Miss Stevens had a share in a discovery of importance, and her name will be remembered for this, when the minutiae of detailed investigations that she carried out have become incorporated in the general body of the subject.”(Thomas Hunt Morgan, 1992)

We can wrap up our document by concluding the fact that Nettie Maria Stevens was a well-known and prominent geneticist of her time. Her work gave people an innovative thought and path to think about and to work on as well as exploring more related issues regarding this matter and other as well.

Still some believe and think that she should be praised more in this filed as she was an recognized geneticist but due to the fact that her discovery of X and Y chromosomes and their role in determining gender is instead generally given by Edmund B Wilson, she is not that famous. Not only this it was also found that Wilson read Stevens’ manuscript on chromosomal patterns before publishing his own theory, he also got assistance by T.H. Morgan, who is fundamentally the biologist with whom Wilson shared the Nobel Prize for the discovery as well.

But besides all of these above-mentioned issues regarding position of Nettie Maria Stevens in this field, it was also seen that her work in this field was still followed and praised not as much but still she can be declared as the first women geneticist who innitiated this point through her research, statements, experment and applications as well.

            After viewing Nettie Maria Stevens work Dr. Thomas Morgan wrote a letter to the Carnegie Institution of Washington in which he mentioned the great capability of Nettie Maria Stevens. He also wrote “Of the graduate students that I have had during the last twelve years I have had no one that was as capable and independent in research as Miss Stevens…”. (Thomas Hunt Morgan, 1992)


·         Nancy Woloch (2001), Women and the American Experience, a Concise History Publisher: McGraw-Hill.
·         Marilyn Bailey and Clifford J. Choquette (1991) “Nettie Maria Stevens (1861-1912): Her Life and Contributions to Cytogenetics,” Proceedings of the American Publisher: Philosophical Society.

·         Thomas Hunt Morgan (1992) “The Scientific Work of Miss N. M. Stevens.” Publisher: Science Society.

·         (1994), Women in Technology News, Magazine: Fall.


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