LETTER 18. RAIN-WATER 119 
but stood some days), they stuck intangled in them; and 
then pulled their body out into an oval, and did struggle, 
by strongly stretching themselves, to get their tail loose ; 
whereby their whole body then sprang back towards the 
pellet of the tail, and their tails then coiled up serpent- 
wise, after the fashion of a copper or iron wire that, 
having been wound close about a round stick, and then 
taken off, kept all its windings.’ This motion, of stretch- 
ing out and pulling together the tail, continued; and I 
have seen several hundred animalcules, caught fast by 
one another in a few filaments, lying within the compass 
of a coarse grain of sand.” 
I also discovered a second sort* of animalcules, whose 
figure was an oval; and I imagined that their head was 
placed at the pointed end. These were a little bit bigger 
than the animalcules first mentioned. ‘Their belly is flat, 
provided with divers incredibly thin little feet, or little 
legs,* which were moved very nimbly, and which I was 
able to discover only after sundry great efforts, and where- 
with they brought off incredibly quick motions. The 
upper part of their body was round, and furnished inside 
with 8, 10, or 12 globules: otherwise these animalcules 
* Apparently it never occurred to L., at this time, that the contraction 
and extension of the stalk (“tail’’) of Vorticella could have any other 
significance than that here attributed to them. The idea of a stalked and 
normally sessile animal probably never entered his head; and consequently 
he jumped to the incorrect conclusion that the animals were endeavouring 
to “ get their tails loose ’’—which, of course, was a mistake, though a very 
natural one. lL. published pictures of Vorticellids later, in Phil. Trans., 
Vol. XXIII (Letter dated 25 Dec. 1702): and still later he arrived at a 
more correct interpretation of the function of the “tail,” and of the 
organization of these remarkable animals (Send-brief VII, dated 28 June 
1713). See Chapter 4, below. 
* inde spatie van een grof sant MS. “ within the space of a grain of gross 
sand” Phil. Trans. This is a very common expression with L., and 
Oldenburg fully understood its meaning ; but Nagler (1918, p. 9) mistranslates 
his words “in der Héhlung eines grossen Sandkorns’’—as though L. had seen 
the animalcules lying in a cavity in an actual grain of sand! 
* Not identifiable with certainty, but undoubtedly a ciliate. 
y Ve ey: 
2.e. cilia. 
