The fonds reflects the scientific and literary outreach activities of the Montreal Natural History Society over the course of its existence and contains correspondence, minutes, financial records, council and committee reports, membership lists, donation lists, catalogues of holdings, newspaper clippings, lecture advertisements and weather maps. In addition, the fonds includes reference material to other societies and information regarding the publication and creation of the Canadian Naturalist and Quarterly Journal of Science, Canadian Naturalist and Geologist and the Canadian Record of Science.

The fonds is composed of the following series: 1) Accounting Records (1860-1917); 2) Administrative Records (1833-1887); 3) Catalogues (ca.1829-ca.1925); 4) Correspondence (1871-1896 with gaps); 5) Essays and Lectures (1829-1852); 6) Minutes (1827-1832,1844-1923); 7) Montreal Microscopical Society (1884-1906); 8) Reports (1828-1881 with gaps); 9) Weather Maps (1895-1897).

These McGill papers are entirely concerned with his property and estate. They comprise legal documents and copies of letters (some in McGill's hand) concerning his land holdings on St. Paul St., Montréal, in Stanbridge, and in Detroit. McGill's cash book, 1809-1815, and copy by W.D. Lighthall of a deed of conveyance to McGill of some land formerly occupied by the city fortifications, 1805, are also included, as is a blue-print and sketch by W.D. Lighthall of the site of McGill's St. Paul St. house. Estate papers comprise a probate of McGill's will, copied by Alice Lighthall, and his executor's cash book.

McDonald's correspondence, 1791-1860, mostly concerns business and property matters, but also includes personal correspondence. There are statements of account with McTavish, Frobisher & Co., 1799; with McTavish, Fraser & Co., 1803-1804; with McTavish, McGillivray & Co., 1808-1809. There are two volumes of autobiographical notes assembled in 1859 and covering the period 1791-1816.

There is a second copy of the autobiography, probably transcribed in the late 19th century. Written on the front fly leaf is the name: A.E. MacDonald. It has 63 leaves, and there are minor textual variants.

The fonds contains Dr. Jacques' journal of medical accounts receivable entered in an account book issued with blank pages and bound in half suede with green cloth boards. The account book was kept between November 1879 and January 1881. A title handwritten on a paper label on the cover reads "Journal pour 1879-1880-1881." The author's full name comes from within the journal (L. A. George Jacques, M. D.) and from Lovell's Montreal directory for 1881-1882 (Louis A. George Jacques, M. D.). Laid in at p. 207 is an ink blotter featuring pharmaceutical advertising for Glyco-Heroin (Smith).

Fonds documents the Mallochs' activities related to their medical and literary work. The fonds contains notes, correpondence, commonplace books, account books, material related to publications, family memorabilia, scrapbooks, photographs, telegrams, postcards and certificates.

Fonds documents Frederick Augusutus Rees' activities as a physician in Bermuda. The fonds contains a ledger, an index to the ledger, notes and letters.

The fonds documents John Bell's activities related to his medical studies at McGill in Surgery, Materia Medica and the Institutes of Medicine, as well as his work as a private physician in Montreal. The fonds consists of notebooks, a photocopy of his MS McGill medical thesis, letters from his personal and professional life, one of his medical kits, receipts from merchants, various subscriptions, societies and clubs. The fonds also contains various reprints of Bell's articles, including the 1878 article, "Case of Diphtheria, Acute Laryngeal Symptoms", as well as the City of Montreal's "Mortality of Montreal" – a list of all deaths in Montreal in January 1878.

Fonds contains the records of the Osler Reporting Society of Montreal from 1929 to 1972, including record books, correspondence, invoices, receipts, list of members, minutes, and constitution.

Fonds contains the financial records of A.R.V. White for his years of private practice. It includes journals, cash books, ledgers and receipts relating to his income and expenditure for his practice in Stanstead, as well as records relating to his bonds and stocks. The fonds contains thirty volumes entitled Journal, Cash book and Ledger filed by year from 1935 to 1964, and a file with loose inserts .

Fonds shows Dr. Allan McMillan's activities as a country doctor in the Eastern Townships of the end of the 19th century. |a The fonds consists of 6 daybooks separated into 6 vols.: v. 1: 22 Apr. 1876-18 Sept. 1885, v. 2: 22 Sept. 1885-7 March 1887, v. 3: 15 March 1894-24 Feb. 1897, v. 4: 1 Aug. 1898-30 June 1900, v. 5: 1 July 1900-8 June 1905, v. 6: 12 June 1905-14 July 1908.