208 NEW YORK STATE MUSEUM 
habits. It is quite probable that with pond culture, as with 
agriculture, when real progress begins it will be necessary to 
recognize not only species, but also varieties of the more im- 
portant species.t 
Notwithstanding the indefiniteness of our knowledge con- 
cerning Chironomus as a whole, it may be worth while to ven- 
ture some general observations concerning the habits of the 
genus, since these will explain some peculiarities of the table. 
Among the larvae attributed to the genus there is consider- 
' able diversity of structure, and a very striking range of color. 
Color differences have led to the distinction “white larvae” 
and “red larvae” in such papers as the one above quoted. The 
distinction is arbitrary, however, and of very limited applicabil- 
ity. The range of color is continuous from bright crimson in 
some of the red larvae to translucent pale yellowish or green- 
ish in the others. Moreover, all are “white larvae” when 
newly hatched; and the red color is correlated with a consider- 
able increase in size without a corresponding development of 
the tracheal system in the body, and is due to the increase 
of hemoglobin in the blood plasma. In general, it may be said 
that the “red larvae” are larger, have a more extensive devel- 
opment of blood gills, and live in deeper or less well aerated 
water; the “ white larvae,” most of which are not Chironomus 
in the stricter sense, are as a rule smaller, have little develop- 
ment of blood gills or of hemoglobin in the blood plasma, and 
live in rapids, on shore vegetation in shallower, cleaner, better 
aerated water. : 
The Chironomus of the foregoing table is one of the larger 
species, with larvae of bright red color. Many of them were 
alive when taken from the trout stomachs, and wriggled about 
as actively as if just taken from the water. In shore collecting 
none were found, but a few of their loose, flocculent gelatinous 
cases were found at the farthest reach of a long handled net 
(depth 5-6 feet), The species is doubtless a denizen of the deeper 
water, which is the proper feeding ground of the trout. It lives 
1Several British Species are characterized in their immature stages, and 
a good general introduction to the study of the biology of the genus is 
now available in Miall © Hammond’s The Harlequin Fly, Oxford 1900. 
