G. H. F. Nuttall 
407 
regarding the causation of infective diseases. In his essay on the Patho¬ 
logical Part of Physic he wrote “and let me add that he that thoroughly 
understands the nature of ferments and fermentation shall probably be much 
better able than he that ignores them to give a fair account of diverse 
phenomena of several diseases (as well as fevers and others) which will 
perhaps be never properly understood without an insight into the doctrine of 
fermentation.” In these words, written some 240 years ago, we trace the 
beginnings of what became the “germ theory” of disease. 
Our portrait is taken from the painting by Frederic Kerseboom in the 
collection of the Royal Society, London. 
Parasitology xm 
27 
