In the largest deal of its kind in the history of American research, a $50 million grant to a Boston hospital has wedded industry and academic science in a joint effort to exploit the new products of genetic engineering.

The Hoechst chemical company of West Germany will give Massachusetts General Hospital $50 million to establish a molecular biology laboratory, in return for licenses to exploit any patient generated in the research. The amount is the largest ever given to an academic institution by industry for research, and the laboratory it will create will be run jointly by the hospital and the Harvard Medical School.

The Hoechst money was accompanied by a $15 million gift from Arthur and Gullan Wellman of Florida to build a laboratory to carry on the genetics work financed by Hoechst.

A principal issue in the negotiations, which began last fall, was acdemic freedom, according to hospital spokesman Martin Bander.

The Hoechst and Massachusettts General deal is the third of recent large corporate entries into the crowded field of gene research. Just across the Charles River from the hospital are the Genetics Institute, which Harvard researchers have helped start, and a second firm forming at the Massachusetts Institute of Technology under Nobel laureate David Baltimore.

An arrangement between a gene engineering company and Harvard University was scuttled last year after a heated debate over what some faculty members said might be industrial intrusiion into the academic enclave.

Nearly all gene researchers at Harvard, MIT and other top institutions are now allied with corporations, according to Mark Ptashne, chairman of Harvard's Department of Molecular Biology. The arrangement between Hoechst and Massachusetts General is the closest alliance yet between a company and an academic institution doing biological research.

Hoechst had considered setting up its own research institute but could not find the right DNA researcher to lead it, according to Howard Goodman, a molecular biologist who will head the new research effort at the hospital.

Goodman has worked on the genetic mechanisms that produce insulin and the human growth hormone. At Massachusetts General he will continue that work and apply the new genetics to plant research.

The new techniques of genetic research -- called recombinant DNA technology -- take genes from one organism and put them into another, for example taking the human gene that makes insulin and putting it into a bacterium, which then can be coaxed to produce relatively large amounts of insulin.

Hoechst is an international chemical company with $16 billion in annual sales and 19 plants in the United States.

Under the agreement, the corporation will not control, or keep confidential, research in the new department. The hospital will keep any patents generated by the research, but will grant exclusive licenses to use them to Hoechst