In 1952 Leon's expertise in insect anatomy and physiology got him a job in London, Ontario with the Canada Department of Agriculture. His work involved excursions to Baie Comeau in Quebec to quantitate the habits of the blackfly, by counting the larvae that swarmed onto inverted white metal cones which were moored in midstream of the rivers. He and his colleagues discovered that blackflies are open for business mainly during the hours of dawn and dusk. In another experiment they sat with patches of different colours on the backs of their shirts, exposing themselves to the blackflies, and found that khaki attracted the least and navy blue the most flies - a boost for the Army as compared to the Navy. During the month of June blackflies in wooded areas of Quebec were an economic disaster and a social nuisance, bringing the forestry work to a slowdown, putting cattle at risk and driving vacationers indoors. The data collected by Leon and his colleagues proved most useful for control of these wood pests.

Leon then decided to go into tropical medicine as a field of study with larger access to bugs and parasites. Since he was next door to the medical school of the University of Western Ontario, he started there in 1954, graduating in 1958 as M.D. with Honours. Aged 32 by this time, he had just met Jeanne, his future wife, who was then a graduate student in geography at Western.

Leon next showed up as an intern at Montreal's Royal Victoria Hospital, which he had picked because of the high reputation of its medical scientists. During this year he became aware of the MNI across the bridge and of Wilder Penfield, Allan Elliott and Ted Rasmussen. A few years earlier Elliott had established the new Donner Laboratory for Neurochemistry and claimed to be the first to use the title "neurochemist". Leon acquired a Fellowship from the National Research Council of Canada (which antedated the Medical Research Council) for a year and a half of study at the Maudsley Hospital in London, England with Professor Henry McIlwain. Ted Rasmussen had just started as Director of the MNI, succeeding Wilder Penfield, and he assured Leon of an appointment as Assistant Professor on his return from England. With McIlwain, Leon characterized the loss of histones from brain tissue kept cold in vitro. And he first became acquainted with the gangliosides in the brain, compounds that would take up his interest over many years.

As you know, our brains are stuffed with hundreds of chemicals. Some are simple - like water - which makes up an embarrassing 80% by weight of our brain, or glucose and oxygen, which supply most of the energy for our thinking. Cut these off for a few minutes and our brains go blank. But Leon's work with his research team dealt with the most complex of brain compounds - esoteric substances such as gangliosides, prostaglandins, leukotrienes, thromboxanes, lipofuscins,