Hie President's Address. By H. G. Plimmer. 127 



Until he was forty years old his name was hardly known to 

 those outside the circle of his friends : and then an event happened 

 which stimulated him to work, more than any other event in his 

 life. His friend, Eegnier de Graaf — he of the Graafian follicle — 

 sent, in 1G73, a notice to the Eoyal Society with this title : " 8|)eci- 

 mens of observations made by means of a microscope invented by 

 A. van Leeuwenhoek in Holland." The notice ends thus: ''So 

 far this observer : who doubtless will proceed in making and im- 

 parting more Observations, the better to evince the goodness of 

 these his glasses." It was accepted, and he wrote : *' I was not a 

 little pleased that my observations about water had not displeased 

 your learned Philosophers." Papers were sent in constantly from 

 this time, and in February 1680 the Fellowship of the Eoyal 

 Society was conferred upon him, his proposer being Dr. Croone, 

 who founded the Croonian Lectures ; and this honour he valued 

 more than anything that happened to him during his whole life. 

 He never came to London to be admitted formally into the Society, 

 but they sent his diploma out to him under quite special con- 

 ditions ; it was sent in a silver box, with the arms of the Society 

 graven thereon, in pursuance of a specially passed resolution. 

 Leeuwenhoek, in acknowledging the diploma, assured the Eoyal 

 Society that he would apply himself to serve them for the rest of 

 his life; and he kept his promise, for he sent them, between 1673 

 and 1722, over 200 letters upon his work, and there are over 130 

 papers by him printed in the Philosophical Transactions : many of 

 these are on various subjects, as the following titles will indicate : 

 " On the edge of razors and on the different tastes of waters " ; 

 ** Teeth, young oysters, eggs of snails, roots of vegetables." He 

 was like Pliny, in that most of his communications took the form 

 of letters. In 1697 he was elected a Corresponding Member of 

 the Academie des Sciences of Paris, to which body he made 26 

 communications. The Eoyal Society ah\ays wanted to obtain 

 more precise information about the instruments he used, and they 

 were also, without doubt, curious to know more of this indefatig- 

 able and strange observer's personality. A circumstance favoured 

 their doing so. One Thomas Molyneux, a zoologist, who studied 

 at Leyden, was going to Holland, and he was asked to go and see 

 Leeuwenhoek. He did so, in February, 1685, and was not 

 altogether charmed. He wrote as follows : " I found him a very 

 civil complaisant man, and doubtless of great natural abilities ; 

 but, contrary to my expectations, quite a stranger to letters, 

 master neither of Latin, French, or English, or any other of the 

 modern tongues besides his own, which is a great hinderance to 

 him in his reasonings upon his observations ; for being ignorant of 

 all other men's thoughts, he is wholly trusting to his own, which I 

 observe, now and then lead him into extravagancies, and suggest 

 very odd accounts of things, nay, sometimes such, as are wholly 



