THE SCIENTIST. 
107 
ences. Ah, there is a little stream down the 
center, and off to the right it forms a little 
lake. Hi, ho! what was that, that moved on 
the lake? Then a ray of light breaks through 
an opening in a passing cloud and for a mo- 
ment the surface of the lake shows vividly, 
and we feel sure that we "see a flock of 
ducks. Gradually we make out other 
objecfs along the stream, a waterfall over 
lime-stone rocks; a heron p'ying his trade 
along the stream; then we turn our attention 
to the varigated verdure alo ig the sides of 
the valley to find here and there clumps of 
foliage that make us sure of the presence of 
the favorite food of deer. 
There! something moved in that pirt of 
the undergrowth, and we exclaim, a deer! a 
deer! but no, out comes a bird, from the 
flight of which we recognize a crow. Hut as 
we continue cur examination, lying partly 
in the shadow and partly in the sunlight we 
see a deer. Directly we find ourselves move- 
ing here and there to get favorrble light, or 
peeping through our hands to cut off sur- 
r unding objects and to better see special 
features of the landscape. 
Why did we make out the little stream 
and the lake first in the landscape? 
Because of the greater reflecting and re- 
fractmg power of water. 
How did we know the disturbance in the 
lake was due to a flock of ducks? Did we 
see a single duck? No, but we saw the 
surface of the lake suddenly lighted by 
a ray of sunlight and on it a moving 
speck, the peculiar outline of which told 
us that it was made up of a num- 
ber of units, and from this outline and the 
relation of the specks to the surface, we felt 
certain of the ducks. 
The sharp outline, marked contrast of 
light gray and black of the waterfall, and 
the ragged fragments of rocks below, made 
us certain it was in a limestone ledge. 
From the characteristic rr.otions of the 
heron, and part of the stream in which he 
waded, we felt very sure that there was fish 
in the water. Yet, as acute as we are, we 
mistake a startled crow for a deer when we 
look into the spice brush and th'nk of thac 
kind of game. And yet while we looked 
over that very part of the field repeatedly we 
did not see the deer, until helped out by the 
light and shade, contrasts of different parts 
of the animal. 
Now if this were a hunting party viewing 
this valley we can imagme one would say, 
that is very hazy seeing ducks on a pond 
when I can hardly make out a heron a good 
deal nearer to us; and the retort, it is about 
as probable as that statement of yours about 
the "Crane'' gawking about catching fish, 
another says; or that the waterfall is formed 
in limestone; another says we thought we 
saw the deer in the spice brush. Then the 
hunter of the party puts the matter at rest by 
saying ducks, deer and fish and a good place 
to camp; here goes, and all follow him to- 
wards the valley. 
Now this is just what happens when we 
study microbes under the microscope: we are 
seeing from about the limit of our vision, 
and must by the aids of sub-stage condensers, 
and stops; and by stains, take every advan- 
tage of light and shade and difference of 
refraction to make out objects. 
Necessarily great differences will arise 
between different observers on account of 
the favorable or unfavorable condition under 
which the same things are seen, and equally 
certayj it is that anticipation, enthusiasm 
and bias lead to the finding of things that 
do not exist. 
The most that can be done in this line is 
to make out and compare forms, as it is not 
possible, as in viewing the landscape, to 
move closer. 
As a check on this means of investigation 
we have the appearance of aggregation of 
these organisms in different media, just as, 
in a landscape, we would recognize a 
clump of a certain kind of foliage when we 
can not see any particular plant. 
Further, we know what results are pro- 
duced in different soils, by the life processes 
of these organisms. 
The living vegetable cells containing chlo- 
rophile, in the presence and from the force 
