742 Mr. Henry George Plimmer [May 2, 



WEEKLY EVENING MEETING, 



Friday, May 2, 1913. 



Sir James Ceichton-Browne, J. P. M.D. LL.D. F.R.S., Treasurer 

 and Vice-President, in the Chair. 



Henry George Plimmer, Esq., F.E.S. F.L.S. F.R.M.S. M.R.I. 



Blood-Parasites 



[Abstract.] 



You will remember that Mephistopheles, when he insists upon the 

 bond with Faust being signed with blood, says, " Blut ist ein ganz 

 besonderer Saft " (Blood is a quite special kind of juice.) Goethe 

 would probably not have used the word " Saft " had he been writing 

 ' Faust ' to-day instead of in 1808, for at that time the cellular 

 elements of the blood — although they had been seen and described 

 by Leeuwenhoek in 1686 — were believed to be optical illusions, 

 even by so distinguished a person as the Professor of Medicine of 

 that time at the Sorbonne. The incredulity of scientific men as 

 to what they see is proverbial and astounding, fortunately ; but it is 

 probably because Science is really quite sure of nothing that it is 

 always advancing. 



I have the privilege this evening of trying to show you the 

 barest outlines of our present knowledge of the parasitology of 

 the blood. It is a subject of great practical and economic im- 

 portance, as many grave diseases of man and beast are caused by these 

 parasites, which, on account of their minuteness, enormous numbers, 

 and very complex life-histories, are very difl&cult to eradicate or to deal 

 with practically. On this account there is a good deal of the enthusiasm of 

 the market-place mixed up with this subject, which, although a new one, 

 has advanced with great rapidity, and has revolutionized pathology, 

 and medicine as far as possible. From our point of view it began in 

 1880 with the discovery by Laveran, in the military hospital of Con- 

 stantine, of the parasite which causes malaria. This caused the 

 protozoa, to which order most of these parasites belong, to oust 

 bacteria from the proud position they then occupied of being the 

 cause of all the ills we have to bear, and to reign in their stead ; 

 not an altogether desirable change ; for when you have seen what I 

 shall show you, you will agree with me that sufficient unto life is 

 the evil thereof. It has had all the disadvantages of a new suljject, 

 and since that time floods of work have been poured into Journals, 

 Annals, Proceedings, etc., some of it of the best, with much of it 

 that is indifferent, temporary, and bad ; so that at times it seems as 



