63 



peculiar gummy substance, which hardens in water, mingled, how- 

 ever, with the latter." — (' Die Infusions-thierchen,' p. 406.) 



I know not what to think of this discrepancy. It is scarcely pos- 

 sible that the experience and power of observation of so excellent a 

 naturalist could have been at fault in a matter, which he himself 

 says he distinctly saw ; and his general care and accuracy forbid us 

 to doubt that what he saw he has correctly recorded. Are there then 

 two modes of effecting the same object in the same animal ? This is 

 scarcely imaginable. Or, are there two species, closely allied, but 

 differing in this part of their organization and economy ? From one 

 or two other slight differences which I have observed, this may be 

 just possible : at any rate it should be borne in mind in future ob- 

 servations. 



The venerable Leeuwenhoek thus describes what he saw, which 

 seems to me sufficiently distinct. " I viewed one of these animals a 

 good while together, and observed several times, one after another, 

 that when the animalculum thrust out its body from the sheath or 

 case, and that the wheel-like or indented particles moved in a circle, 

 at the same time, out of a clear and transparent place, a little round 

 particle appeared, which without nicely viewing could hardly be per- 

 ceived ; which particle growing larger, moved with great swiftness, as 

 it were about its own axis, and continued without any alteration in 

 its place, till the animal had drawn part of its body back into its 

 sheath ; in doing which it placed the said round particle on the 

 edge of its sheath, which thus became augmented with a round glo- 

 bule ; and whereas the animalculum had placed the said globule on 

 the east part of its sheath, another time it fixed it on the south or 

 north side ; by which means the sheath was regularly increased on all 

 sides." — Phil. Trans, iv. 43 (abridged edition). 



I would again observe that I had not the slightest acquaintance 

 with these observations, till some time after I had made the whole of 

 my own ; which were recorded with the animal before my eye. 



