478 
POPULAR SCIENCE REVIEW. 
accumulates on the phial’s side for food; now and then 
shooting off into the water, and swimming evenly and grace- 
fully along, slowly rotating on their long axis as they go. 
Their movements can he watched, and their forms distinctly 
made out, with the aid of a good pocket-lens, as the phial 
stands on the window-sill ; and this sort of observation, which 
is highly interesting, can be pursued with great ease and 
satisfaction, especially if the finger of the disengaged hand 
be passed behind the phial (without shaking it), so as to 
intercept those rays of light which pass direct from the sky 
through the animalcule to the eye of the observer. The 
effect of this manoeuvre is to make a dark back-ground for 
the object, while it is yet brilliantly illumined by the rays that 
fall on it from all around the finger. Small as is the magni- 
fication, (the experienced observer has no difficulty in distin- 
guishing the principal organs, which, under this mode of 
illumination, have a relief and a solidity which are very 
instructive. 
But I must describe our little beauty in detail. Its body is 
nearly a cylinder, of about a hundredth of an inch in length, 
with a diameter of one-third the length. Sometimes it 
becomes almost pear-shaped, by the swelling out of the hinder 
half of the body, when an egg is maturing in the ovary. In 
the ItoTiFERA generally, the eggs are of immense size in 
proportion to the body ; and in this species they are even 
larger than usual, an egg just ready for discharge occupying 
nearly one-fourth of the entire volume of the animal. In 
the figure such an egg is seen occupying a large space just 
behind the middle of the animal. 
The head is capable of considerable alteration in shape. 
When the animal is busy feeding, resting on its two-toed foot, 
with the body thrown forward horizontally, the front of the 
head is so oblique that, by a little bending downward, 
producing some strong foldings of the skin of the breast, it 
can be brought, as a nearly flat surface, into contact with the 
ground. A specimen is represented in this position, under a 
lateral view, in fig. b. The action of the frontal cilia is then 
seen, as if evenly covering this surface, producing' currents, 
which, however, do not form whirlpools. But suddenly the 
little animal ceases feeding ; rears itself' on its toes till it stands 
nearly erect ; balances itself for a moment ; evolves from each 
side of the head, by a kind of turning inside-out, a remark- 
able ear-like process, which is clothed with much stronger 
cilia. The action of these immediately begins to form vigorous 
circular vortices, of which the “ ears ” are the centres, and in 
the same instant the animal shoots forward with beautiful ease 
and precision, on its even course, revolving slowly as it goes. 
