Last summer, I had the opportunity to examine the history of what is now called the Asa Gray Collection as part of the Michigan Library Scholars Internship Program. This collection represents the foundation of the University Library's collection and was formed when Professor Asa Gray was comissioned to purchase books for the new university. The research for my project culminated in a website which maps both the European travels of Asa Gray as well as the movement of Gray’s book purchases into the United States.
Although the website is valuable for connecting Gray’s purchases to their countries of origin (and their subsequent "homes" at the University), a basic understanding of the Gray purchase is important, too. That being said, what follows is an informative (and very brief) outline of the Gray purchase.
After Asa Gray’s appointment as the University’s first professor, the Board of Regents decided to send him abroad to purchase academic materials. To Gray, this meant more than books; he hoped to furnish the University with the latest scientific equipment.  But the new University had to act frugally, so the Regents decided that Gray should only purchase books. 
It is difficult to gauge Gray’s interest in his “book-buying” task, and scholars like Russell Bidlack (among others) have suggested that George P. Putnam--an American bookseller whom Gray befriended in London (and who was also the publisher of Gray’s scientific work with his mentor)--chose most of the library books.  This is most likely the case, as Putnam would have had more contacts in the world of bookselling than Gray, allowing him to procure a high volume of books for a significantly lower price.  Gray was not completely unattached from his original mission, however. Though he did mention in his letters that he had fallen behind in acquiring books for the University, there are points in his European tour where he suggests his own involvement in the book-buying process. 
Despite Gray’s background as a botanist, the book purchases that can be attributed to him especially highlight the humanities. As Bidlack suggests, this may be due to his own personal interest in subjects like history and literature.  This choice in subject matter seems unusual given Gray’s medical/scientific background and the fact that history was not part of a typical university’s curriculum at the time. 
The purchased books finally arrived in Ann Arbor, yet they were stored in one of the professors' houses until Mason Hall -- which would serve as the students’ dormitory as well as classroom, chapel, and library -- was built.  However, the books did not remain in a single building for long; not only did the University change the site of its library from Mason Hall to the Law School to the actual library, but many academic departments had their own libraries.  Thus many of the books from the Gray purchase lived, at one point in time, on bookshelves in the Chemistry Library, the Mathematics and Economics Library, and the Architecture Library to name a few.
Today, much of the material from the Gray Purchase is held in the Special Collections Library and can be consulted in the Special Collections Reading Room. Many volumes have also been digitized and so can be accessed online through the HathiTrust Digital Library. The University Library's collections have vastly expanded from the initial 3,400 volumes selected by Gray and Putnam and continue to grow year after year.
 Russell E. Bidlack, The University of Michigan General Library, a History of its Beginnings, 1837-1852. (PhD diss., University of Michigan, 1954), 120.
 Ibid, 120.
 Ibid, 127.
 Ibid, 157.
 Asa Gray, Letters of Asa Gray, Edited by Jane Loring Gray. Vol. 1. (Boston: Houghton, Mifflin and Company, 1893), 266. In his letters from Paris, he mentions shopping for books which also may be where he acquired titles himself; see also Bidlack 1954, 127.
 Russell E. Bidlack, The University of Michigan General Library, a History of its Beginnings, 1837-1852 (PhD diss., University of Michigan, 1954), 141.
 Ibid, 141.
 Ibid, 159-160.
 Bidlack’s Catalogue regarding the “Gray Purchase,” which begins on page 321 of his dissertation, makes note of the library in which the title is located, as several of the titles were not part of Special Collections or the Hatcher Graduate Library.