114 
THE MOTION OF THE CILIA OF ANIMALCULA. May, 1890. 
shel marl, and a bed of peat caps the whole. Subsequent 
to the emergence of the land, a small lake lay in this hollow. 
Fresli-water molluscs flourished in its waters, and their com¬ 
minuted shells accumulated to form the marls. Then the pool 
was choked up with vegetation, and became a bog. The lake 
deposits of Shropshire have yielded human implements, and 
belong to a comparatively modern prehistoric epoch. They 
should be looked for throughout the county, and should be 
searched for the remains of man and his handiwork. 
While these more recent formations are of much interest, 
I have laid greater stress upon the glacial deposits. It is in 
these that the evidence of man’s existence becomes of peculiar 
value. No one questions the fact that men lived in the Lake 
Period, but how far their history can be traced back into the 
dimmer ages is still an unsettled question. A careful study 
of the superficial drifts of this county may help us to 
approach a solution.. If we share the sentiment of Terence— 
“Nil kumani alienum a me”— 
we shall find the search for flint implements one of the most 
fascinating that can engage our attention, and shall discover 
new confirmations of the belief that “ thro’ the ages one 
increasing purpose runs.” 
ON THE MOTION OF THE CILIA OF ANIMALCULA 
AS SEEN BY FLASHING LIGHT.* 
BY GEORGE J. BURCH, B.A., OXON. 
The subject matter of my lecture to-night falls naturally 
into three sections—the Problem, the Apparatus, and the 
Results. 
The problem is this :—There are a certain number of 
animalcules which appear when in the act of seeking their food 
as if their heads were surrounded by spokes, as of a wheel 
without a tire in rapid rotation. So remarkable is this appear¬ 
ance that it suggested at once to their discoverer the name of 
Rotifer, or wheel animalcule, by which they are universally 
known. But among the innumerable varieties of appendages 
and limbs, and the countless forms of joints and articulations 
and adaptations of various organs to the needs of their 
owners, we have no instance of the wheel and axle. Evolu¬ 
tion draws the line at that “ simple machine.” 
Plainly, then, this appearance of a wheel revolving must 
be an optical illusion. This fact, indeed, was recognised by 
*A paper read before the Oxfordshire Natural History Society 
February 11th, 1889. 
