Entomology. 1131 
If the space between the two plates of glass be very narrow, when 
the seeds which have been sown in this cage germinate, a large part 
of the roots will ramify in the soil so near the surface of the glass 
that they may be easily seen by simply removing the piece of 
zine already described. When the plants have become well estab- 
lished they may be infected with the insect pest to be studied, 
and continuous observations can be made without disturbing them. 
Thus at the present time I have corn growing in these cages with 
Wire-worms feeding upon its roots. In other cages I have clover 
growing, the roots of which form an almost continuous mat on the 
inner surface of the cage. Better results can be obtained in this 
way than by going into the fields and digging up plants; for in 
most cases the moment plants are dug up the insects stop their 
work, while in these root-cages continuous observation of the same 
insect is possible. 
_ I haye had constructed several large root-cages, the frames of which 
are of iron, and each side of which consists of eight lights of glass, 
each ten inches by twelve inches in size. A pit has been dug for 
the reception of each cage; these pits are walled with brick. 
When the cage is placed in the pit, the top of it is even with the 
surface of the ground ; by excluding the light from this pit it is 
hoped that the roots can be kept under nearly normal condition. 
These cages have been constructed for larger plants; thus we 
a ae to plant apple-trees in some, for the study of the root 
orm of the Woolly Aphis of the apple; grape-vines in others in 
order to observe the Grape Phylloxera; and hop-vines in still 
others for use in proposed experiments upon the Hop Plant-louse. 
These cages are lifted from the ground when it is desired to study 
them by means of a small portable derrick. 
Another form of breeding-cage which I have found very useful 
is made by combining an open-top bell-jar and a flower-pot. The 
food plant of the insect is either growing in the pot or is stuck into 
wet sand in the pot and kept fresh as a gardener would keep a cut- 
ing. large saucer is used, and an inch or more of sand is placed 
in it. The bell-jar is placed over the plant in the pot and pressed 
down into the sand in the saucer. The open top of the bell-jar is 
covered with swiss muslin. The plant or cutting can be kept 
well watered by pouring water into the saucer without removing 
the bell-jar. The layer of sand in the saucer saves from drowning 
those insects that crawl down from the plants. The circulation 
of air through the muslin at the top prevents the formation of 
I have long used jelly-tumblers and fruit-jars for —— small 
ir and for storing pups. I have been much annoyed by ina- 
bility to preserve the proper degree of moisture in these receptacles 
If they are supplied with moistened sand and closed tightly the 
