THE PRESIDENT'S ADDRESS. 439 



and fundamental principle, or, on the other hand, will prove 

 ultimately to have some direct or indirect bearing on human 

 life and its needs. Let me give two instances in support of 

 this statement. To the so-called practical man it may seem 

 a very trivial occupation to worry about such things as Forami- 

 nifera, however beautiful their shells may be. Yet these tiny 

 creatures, living in a sphere apparently so remote from our own, 

 furnish wonderful illustrations of the powers and activities of 

 primitive living matter, and Mr. Earland has recently drawn 

 our attention to the remarkable property they exhibit of selecting 

 particular materials for building up their houses. This is a most 

 interesting fact, well worthy of further study, especially by 

 experimental methods, for it indicates that the most primitive 

 and formless living matter possesses faculties of a kind which we 

 term in higher forms of life instinct or intelligence. Again, 

 a reputation for being an expert on, let us say, fleas may provoke 

 a smile from the uninstructed ; but in view of the proved con- 

 nection between fleas and human disease, especially plague, these 

 paltry insects have now assumed very great importance as objects 

 of study, and we find detailed descriptions of them in the reports 

 of Government commissions. As Lord Crewe remarked in a 

 recent speech, we commonly speak of any very trivial annoyance 

 as a flea-bite ; but we know now that under certain circumstances 

 a flea-bite may cost a man his life. .Small wonder, then, that fleas 

 have become important objects of study to mankind. 



This question of fleas and plague reminds me that I am here 

 not to preach a sermon, but to give an address, by recalling to my 

 mind the subject which I propose to discuss to-night, namely, 

 some of the remarkable advances that have been made during 

 the last few years in our knowledge of human diseases caused by 

 microscopic parasites. This is a subject which has now grown to 

 such vast proportions that I must confine myself of necessity to a 

 small part of it, namely, the diseases caused by Protozoa. As 

 examples, I shall deal more especially with malaria, sleeping 

 sickness, and yellow fever. 



Malaria is a disease which was well known to the ancients, and 

 is still very rife in many parts of Europe. It appears to have 

 been prevalent formerly in the fen districts of England, but 

 to have died out there from some unexplained reason. It is 

 estimated by Prof. Ronald Poss to cause from a quarter to 



