()•*> 
erv large, to prevent tlie possible introduction of the leaf louse 
•y outside females producing young upon the cloth where the 
orn leaves touched it. The earth within the inclosures was 
horoughly disinfected, and planted to corn in the spring, and 
olonies of ants were started here and kept continuously sup- 
lied with corn-root lice throughout the season, the object be- 
ig to ascertain whether the evolution of the- aerial louse would 
ccur under these strict conditions. We have also repeatedly 
ried the direct transfer of root lice of various generations to 
he corn leaf, inclosed in a way to preclude outside interference. 
The principal facts arrived at can be most conveniently given 
11 the form of a biographical narrative extending through the 
ear. 
The root louse hibernates as an egg in the earth, and, as 
a»r as known, only in the nests of ants of a species identified 
3r me by August Forel as Lasius brunneus , var. alien us. This 
nt is host and constant companion of the root louse through- 
»ut the year. It is equally devoted, however, to the common 
;rass-root louse (Schizoneura corui, by Osborn’s determination), 
die ant above referred to is the common small brown ant 
Tout an eighth of an inch in length, abundant in corn fields 
n spring, where it burrows among the roots of the corn. Its 
lests are still more common along the borders of roads and 
•atlis through pastures and other grass lands.. The formicaries 
ontaining the corn-louse eggs are most frequently to be found 
n old hills of corn, late in autumn or in early spring, at a time 
• hen the ants are torpid within the earth, and when, conse- 
uently, their mining operations do not betray their presence, 
diey should be sought by digging or plowing up the corn stub- 
tie in the field, when, if ants be found, a thorough search of 
he burrows will commonly show the minute, oval, shining black 
phis eggs piled together in larger or smaller quantities, the 
epth below the surface varying according to the season, and 
ven the time of day. We have found them at a depth of 6 or 
inches, and again scarcely more than half an inch below the 
urface. In spring especially, when hatching time draws near, 
he ants convey the eggs to the upper galleries of their nests 
luring the heat of the day (particularly if the weather be fine), 
>ut withdraw them for the night and during cold wet days. 
The ants themselves pass the winter as adult workers, and as 
arvse in various stages from the minute young to those nearly 
idl grown. The time of hatching of the plant-louse eggs varies, 
>f course, with the season, ranging, according to our observat¬ 
ions, from the 10th to the 30th of April. The commencement 
>f the hatching season is fairly well indicated by the opening of 
he radical leaA^es of the common smartweed or heartweed 
Polygonum persicaria) in the fields. The greater part of the 
ggs are commonly hatched a, week or ten days before corn 
Wanting is fairlv under wav. 
—5 
