Frederick Banting upon the idea of obtaining insulin from the fetal pancreas. He removed the pancreases from fetal calves at a William Davies slaughterhouse and found the extracts to be just as potent as those extracted from the dog pancreases. By December 1921, he had also succeeded in extracting insulin from the adult pancreas. Pork and beef would remain the primary commercial sources of insulin until they were replaced by genetically-engineered bacteria in the late 20th century. In spring of 1922, Banting established a private practice in Toronto and began to treat diabetic patients. His first American patient was Elizabeth Hughes Gossett,
Highest and best use to the developer and this makes it the maximally productive use. In reality, short term constraints on availability of capital and labour, inevitable conflicts between the other key factors, as well as the predisposition and experience of the developers, often lead to developments that are not maximally productive, but are a compromise. They are productive enough and safe enough that the developer proceeds, but they are not maximally productive. James Graaskamp fully developed a model that reflects this reality more clearly, and termed it most probable use. The Test of Highest and Best Use is applied to an improved property