12 THE BRADSHAW LECTURE 



Malaria. 



Not many years ago malaria was described as 

 a climatic diathesis, by which it was intended 

 to imply that a constitutional condition was 

 brought about by residence in certain climates, 

 and that it became hereditary. The protozoon of 

 malaria was discovered by Laveran in 1880, and 

 its life history and mode of inoculation has since 

 been so clearly demonstrated that any idea of its 

 being associated with a diathesis would strike 

 everyone now as being utterly absurd. 



Cancer. 



The diathesis of cancer was never asserted 

 with the same absolute confidence as was that of 

 tuberculosis, and the profession has been about 

 equally divided as to whether it was an hereditary 

 disease or not. Sir James Paget taught that it 

 was a blood disease, which caused local manifesta- 

 tions, but the evidence of its commencement as a 

 local disease is now overwhelming. John Birkett, 

 at one time a great authority, going over his 

 cases, found cancer more common in families 

 without history of cancer than in those families 

 in which there was a history of the disease, and 

 Paget could only trace a family history in one 



