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SCIENTIFIC METHOD IN BIOLOGY
see his father, who had felt unwell ever since the shock of seeing the pathological plate. He was found suffering from the first symptoms of an illness which proved to be an attack of confluent small-pox. The most searching inquiry failed to discover any traces of the disease, either in the neighbourhood or in any connection whatever with the patient. The cause of this illness, one of the most severe cases the doctor had ever met with, remained a mystery.
It has become of vital importance to investigate 'how far the mental attitude determines or permits the onset of infectious disease.'
