Avery was one of the first molecular biologists and a pioneer in immunochemistry, but he is best known for the experiment (published in 1944 with his co-workers Colin MacLeod and Maclyn McCarty) that isolated DNA as the material of which genes and chromosomes are made.

[10] He remained as a pastor for 14 years in Halifax before traveling to the Mariner's Temple in New York City, where he would preach to a rowdy and poverty-stricken crowd.

[11] While here, he would publish an edifying pamphlet entitled "The Voyage of Life", edited the church publication Buds and Blossoms, and patented and attempted to sell a preparation known as "Avery's Auraline", though it would gain little success.

[12] When their home burned to the ground in December 1890, the Baptist community of New York banded together to help pay for the expenses, including one John D.

[13] Avery's mother, Elizabeth Crowdy, was the beating heart and soul that made her husband's church the community center it was.

[14] She would also continue to work with the Baptist City Mission Society, where she would come into association with a number of wealthy people, including the Sloans, the Vanderbilts, and the Rockefellers.

Oswald Avery was born and grew up in a small wooden row house on Moran Street in the North End of Halifax, now a designated heritage building.

[18] In Avery's senior year, he and a few of his classmates asked their philosophy professor to create a metaphysics class that would allow them to explore the credibility of the Christian faith.

[21][20] Oswald Avery began medical studies at The College of Physicians and Surgeons at Columbia University in New York later in the year of 1900.

[24] At Hoagland Laboratory, he began by studying the bacteriology of yogurt and other fermented milk products and their effects on gut bacteria.

[27] In 1911, Avery instructed staff of H. K. Mulford Company in bacteriological techniques, and they taught him the industrial methods for production of antitoxins and vaccines.

[28] At the institute, Cole, Avery and Alphonse Dochez developed the first effective immune serum against a strain of pneumococcus, a bacterium causing pneumonia.

[31] Avery wrote about the results of his findings in a 1915 paper called "Varieties of Pneumococcus and Their Relation to Lobar Pneumonia".

[32] In the paper, he argued that people who appeared to be healthy could be carriers of pneumonia[32] Avery also suggested it was important to identify the type of strain, based on agglutination of the pneumococci, when determining the appropriate serum for the patient.

[32] Avery wrote the monograph, Acute Lobar Pneumonia: Prevention and Serum Treatment, that was published by The Institute explaining this improvement.

[33] Avery also helped Dochez in his research on specific soluble substances found in the blood and urine of pneumonia patients.

[34] The presence of specific soluble substances in a urine sample allowed him to rapidly test the type of pneumonia without having to wait for a culture to grow.

[36] Their work with specific soluble substances showed that it is important to consider the factor in the chemical composition of organisms to design anti-serums.

For that purpose, he developed improved culture media for B. influenzae, which were widely adopted and reduced the possibility of false negatives.

Continuing the research done by Frederick Griffith, Avery worked with Colin MacLeod and Maclyn McCarty on the mystery of inheritance.

He had received emeritus status from the Rockefeller Institute in 1943, but continued working for five years, though by that time he was in his late sixties.

In 1944 at the Rockefeller Institute's Hospital for medical research, Oswald Avery, along with Colin MacLeod and Maclyn McCarty, isolated S-strain bacteria and killed them with heat.

[43][44][42][41] Avery's conclusion, that "The evidence presented supports the belief that a nucleic acid of the desoxyribose type is the fundamental unit of the transforming principle of Pneumococcus Type III" greatly influenced Erwin Chargaff, who upon reading those words dedicated his work to identify a "chemistry of heredity" which he later elucidated in Chargaff's rules.

These experiments paved the way for Watson and Crick's discovery of the helical structure of DNA, and thus the birth of modern genetics and molecular biology.

Of this event, Avery wrote in a letter to his youngest brother Roy, a bacteriologist at the Vanderbilt School of Medicine: "It's lots of fun to blow bubbles but it's wiser to prick them yourself before someone else tries to.

"[46] Nobel laureate Joshua Lederberg stated that Avery and his laboratory provided "the historical platform of modern DNA research" and "betokened the molecular revolution in genetics and biomedical science generally".

While working at Rockefeller Institute, Avery contracted Grave's disease, which caused him to experienced mood swings of depression and irritability.

[48] While in the southern United States, Avery took a particular interest in the local flora and would act as a gardener would, learning about and appreciating the flowers and trees.

Many of his papers, poems, and hand written lab-notes are available at the National Library of Medicine in the Oswald T. Avery Collection, the first of their Profiles in Science series.