360 LEEUWENHOEK AND HIS ‘‘ LITTLE ANIMALS” 
others), and I therefore felt satisfied that the letter was written 
by Leibniz and not by Leeuwenhoek. This I was soon able to 
confirm by discovering that the manuscript in question had 
actually been published previously as a genuine Leibniz letter 
by Targioni-Tozzetti (1746, pp. 119-122). 
Leeuwenhoek’s own seals have never yet been described. 
At various periods of his life he sealed his letters with at least 
three different ones—usually of red wax, but occasionally of 
black. Most of the extant impressions are imperfect—the 
seals having generally been broken, of course, in opening the 
letters. The following notes are put together from the avail- 
able fragments. They may assist future students in identifying 
his writings, but are as incomplete and imperfect as their 
originals. : 
(1) Most of the early epistles are sealed with the monogram 
shown in Plate XXXII (upper figure). This is taken from an 
almost perfect impression on Letter 3a (16 April 1674)— 
stamped from an oval die measuring approximately 16 mm. by 
14mm. The letters APL presumably stand for A[ntony] 
P[hilipszoon| L[eeuwenhoek] ; the rest of the device I cannot 
interpret with any confidence. Above, there appears to be an 
arabic numeral 4: below, connected by a vertical line, the 
roman figure xx or (more probably) xxv can be read. 
(2) Another early seal—which I am unable to reproduce— 
was a heraldic device, all extant impressions of which are 
more or less fractured or indistinct. The die was apparently 
oval, about 17 mm. by 16 mm., with a slightly beaded border. 
The available examples show a small shield, bearing four 
raised vertical lines, surmounted by a helmet. On the field 
behind are various irregularly distributed plumules (?), but no 
lettering or other recognizable figures. This seal is affixed to 
several early signed and authentic letters to the Royal Society 
(including No. 13, 20 December 1675, from which an extract 
is here translated). The armorial bearings I have been unable 
to identify. I can only add that an identical scutcheon with 
four vertical lines is several times figured by Boitet (1729) as 
the coat-of-arms of the Uttenbroek family—a family with 
which Leeuwenhoek is not known to have been connected. 
(3) Nearly all the later letters, when sealed, bear a portrait 
of Leeuwenhoek himself. The die used for this seal (see 
Plate XXXII, lower figure) was evidently cut with very great 
care and precision, and the various impressions—in red (rarely 
