Frederick Banting realized that this procedure would destroy the trypsin-secreting cells but not the insulin. Once the trypsin-secreting cells had died, insulin could be extracted from the islets of Langerhans. Banting discussed this approach with J. J. R. Macleod, Professor of Physiology at the University of Toronto. Macleod provided experimental facilities and the assistance of one of his students, Charles Best. Banting and Best, with the assistance of biochemist James Collip, began the production of insulin by this means. As the experiments proceeded, the required quantities could no longer be obtained by performing surgery on living dogs. In November 1921, Banting hit
Highest and best use Since their use predates these regulations, they are "grandfathered in". However, some such uses may not be reproduced if the legally nonconforming improvement is destroyed or damaged beyond a certain point. "Legally permissible" can be a tricky conceptual test, because even uses that are currently not permitted may be considered. This happens when there is a reasonable prospect (at least 50%) that the regulation, zoning, deed restriction, etc. can be changed to permit the proposed use. Any potential use must be physically possible given the size, shape, topography, and other characteristics of the site. For example, a single story warehouse