Sir Michael Foster standing in front of a blackboard. Photogravure after the Hon. John Collier.

The portrait "presents him in professorial mode, as in a lecture theatre, with chalk in his hand and on the blackboard a list of substances that were then regarded as necessary for human physiological function. Indeed the list appears to be taken directly from chapter or lecture 12 in the textbook Physiology for beginners, published by Foster and his Cambridge colleague Lewis E. Shore in 1894: 'From the cavity of the alimentary canal the useful parts of the food – the proteids, carbohydrates, fats, salts and water – are absorbed, that is, they pass into the tissue forming the wall of the alimentary canal … By the process of digestion the food materials are rendered capable of absorption and of assimilation. These changes are chiefly brought about by the action on the food of certain juices which are prepared – secreted, as it is called – by certain tissues, and are poured into the cavity of the alimentary canal … the saliva, the gastric juice, the pancreatic juice and the bile.'"--Marsh, op. cit.