42 NATURAL HISTORY OF THE FARM 
equipped for fighting, cannot afford to 
be conspicuous. Butif one will reflect 
that carnivores can not maintain 
themselves indefinitely by eating one 
another, and will look a little more 
closely, he will find plenty of the 
herbivorous forms. These are they 
whose economic function is that of 
“turning grass into flesh, in order that 
carnivorous Goths and Vandals may 
subsist also, and in their turn pro- 
claim ‘All flesh is grass’”’ (Coues). 
The most widespread, abundant, 
Fic. 23. Immature stages and important of the herbivores of the 
of four common neuropterous 
insects: a, adragon-fly (Anax 4 
insectst a, @ dragon-fly (4raz stream are apt to be the scuds (Fig. 
(Amphiagrion amphion); ¢,a 20), the may-fly nymphs (Fig. 23, d), 
stone-fly (Acroneuria sp?); 
d,amay-fly (Callibetis s6?). and the larvee of midges (Fig. 24,d). 
Study 4. The Farm Stream 
This study assumes that there is accessible some creek, or 
large brook or small river, having rapids and shoals and pools 
and reed-grown bays in it, all easy of access. If the banks 
where the work is to be done are too soft, rubber boots for 
wading, or temporary walks that will make wading unneces- 
sary, will have to be provided. Each student should be pro- 
vided with a dip-net for catching specimens, a shallow dish in 
which to examine them, a lifter with which to transfer them, 
and a few vials in which small specimens may be examined 
with a lens. 
A normal condition of the stream is necessary; high water 
and great turbidity will render the work unsatisfactory. 
Program—Go over the area marked for examination, begin- 
ning with the pools having mud bottom, and proceeding to 
