Tlie President's Address. By H. G. Plimmer. 135 



results have been obtained in the space of a few years, and no one 

 can say what the future has further to tell us. There is much for 

 it to tell, for we know the complete life- histories of but very few 

 of the organisms causing the diseases above mentioned. Their 

 various life-stages are very complex, and it behoves us to tread 

 very warily in observation, and not to hurry in the interpretation 

 of our observations. For we really know dangerously little about 

 all these things, although our aim is the largest possible knowledge 

 of living beings, especially of those that are infinitely little, and our 

 work is to make these little things look big (the word "magnify "), 

 which is of no harm if we remember that the things themselves 

 are really no bigger than they were before, so that we do not lose the 

 power of appreciating the relative size and importance of things, 

 and do not make our accounts of them sound too harmonious be- 

 fore we have found half the notes of the chords we blow. We have 

 at present to be content to know these organisms rather as the 

 hunter knows his tigers and wild-boars than as the zoologist knows 

 his species, his genera, and his orders, by description of compara- 

 tive characters. 



Perhaps it is even a mistake to be too scientific, because in 

 research of this kind one has to deal with the unknown rather than 

 with the known ; and science is bad in dealing with the unknown. 

 For instance, some of the more known of the blood parasites have 

 ten or more different names, given by different workers and sys- 

 tematizers ; the zoologists are great sinners it seems to me in this 

 respect, perhaps on the Socratic principle that naming saves so 

 much thinking ; the thing is labelled and put away, there it can 

 rest ! But these namings are really absurd until we know the 

 complete history of the organism, and it would seem as if this 

 branch of science were in danger of being smothered in the dust of 

 its own workshop. 



I have mentioned Laveran's discovery of the malaria parasites 

 inside the red cells of the blood as being the starting point of this 

 branch of research ; so it was, but the first mention of a blood- 

 parasite dates from 1841, when A'alentin found what he called an 

 entozoon in the blood of a fish, Salmo fario, and Gruby, in 1843, 

 gave the name Trypanosome to an organism he found in the blood 

 of a frog. 



During the last twelve years I have been working at the different 

 manifestations of trypanosomes in man and animals, and for the last 

 four years I have had the opportunity of being able to examine all 

 the animals which have died in the Zoological Gardens, so that 

 I have examined microscopically altogether about 8000 different 

 specimens of blood of mammals, birds and reptiles, using this latter 

 word in its largest sense, as including amphibians. In 447 of 

 these, a little over 5 p.c, I have found parasites, in 256 different 

 species of animals ; for I found that sometimes every separate 



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