TESTES OCULATI ney 
All these attestations bear out what Leeuwenhoek himself 
tells us in his letters. But they also tell us that the capillary 
glass tube containing the animalcules was as thick as a horse- 
hair * (Haan and Cordes), and that it was divided into a large 
number of measured parts, though it contained but a droplet 
of water no bigger than a millet-seed. Hodenpijl says the 
animalcules looked to him as large as lice, or even larger’: 
while Haan and Cordes declare that some of them appeared 
as big as bugs." 
To the testimony of these worthy men we may now add 
that of Christiaan Huygens, who, at the end of his French 
version of Leeuwenhoek’s observations,’ added the following 
remarks of his own’: “These are the observations of Mr. 
Leeuwenhoek. His manner of making them is to introduce 
the water into very little glass tubes, one third or one quarter 
of a line in diameter; and these he afterwards applies to his 
microscopes. He showed me some of these little insects very 
distinctly, continually tumbling about in the water”. We 
may suppose, accordingly, that Huygens, when he wrote this, 
had overcome his original scepticism regarding Leeuwenhoek’s 
observations. Indeed, the demonstration of which he here 
speaks was probably the stimulus which prompted him, soon 
Judith le Roy, and he has found records of the baptism of three of their 
children (circiter 1668): but he has been able to find out nothing of present 
interest about him in the Archives of Delft. It seems probable, however, 
that Aldert H. is identical with Aalbert H. who is recorded in Boitet (1729, 
pp. 519-20) as having been schutterkoning (= champion shot) of Delft in 
1661, 1665, and 1668. (The discrepancy between ‘‘ Aldert ”’ and “ Aalbert” 
may be easily accounted for—Mr Bouricius assures me—by the “ general 
slovenliness [slordigheid] in writing names at that time”.) Why L. sent 
his testimony I do not know—unless it was because his pre-eminence in 
shooting guaranteed the excellence of his eyesight. 
‘ad crassitiem pili equini crasso MS. 
* Haan and Cordes say 50 parts, Hodenpijl says 70, and Boogert and his 
co-signatories say 90. No doubt the discrepancy is to be explained by the 
circumstance that they recorded L.’s procedure on three different occasions. 
* hebbende de groote van een luijs, en sommige grooter MS. 
*apparebant ad magnitudinem cinvicis MS. 
> See p. 115, note 6. 
° Published in Guvr. Compl. de Chr. Huygens, Vol. VIII, p. 27. These 
remarks remained in manuscript until 1899, when this volume was published. 
The original is in French, and the above is my translation. 
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