40 LIFE HISTORY OF NORTH AMERICAN TICKS. 
days in the bag attached to the host. In the observations here 
recorded those that had not attached at the end of 24 hours were 
removed from the bag. Others that might not have attached but 
that were upon the host were permitted to remain. Thus the 
' observations reported actually indicate what takes place in nature. 
In a few instances rabbits, guinea pigs, and fox squirrels have 
allowed ticks to become engorged when no provision was made to 
prevent the host from scratching. Usually, however, special pre- 
cautions must be taken to prevent the host from displacing the 
parasites. With most of the small animals, a leather collar has been 
successfully utilized. These collars are made by cutting out a 
disk-shaped piece of leather with a hole in the center slightly larger 
than the neck of the animal. The width of the collar should be at 
least equal to the distance from the neck to the chin. In applying 
the collar the ends are lapped and fastened with brass rivets. By 
keeping the outer edge of the collar circular, the disk takes the form 
of a truncated cone with base extending forward around the head. 
(See Pl. I, fig. 6.) When dogs are used, a leather band 4 or 5 inches 
wide should be placed around the neck behind the other collar so as 
to keep it forward. In order to protect ticks attached on the ears of 
rabbits, a disk-shaped collar made of light boards is employed. 
This collar should be made in two parts, the halves being fastened 
together with rubber bands so as to permit of removing the collar 
easily and to make it flexible. © 
As the engorged ticks are removed from the bag or tray, it has 
been found that favorable conditions for further development are 
furnished by placing them in pill boxes upon moist sand. These 
pill boxes are prepared by puncturing the tops and bottoms, or still 
better, they are furnished with gauze tops, to permit of free circula- 
tion. Still more favorable conditions are furnished by inserting 
sand in test tubes from which the bottoms have been removed. 
The bottoms of tubes may be removed in a satisfactory manner by 
plunging the tubes into cold water after they have been heated by 
friction produced by rubbing with a string wrapped around the tube 
at the point where the cut is desired. These tubes should always 
be used with those species which, in the immature stages, have a 
habit of burrowing into the sand before becoming quiescent. As 
stoppers for the tubes, absorbent cotton will largely prevent too 
humid an atmosphere, if protected from rains. A large tray, as 
shown in Plate II, figure 2, has been used filled with sand into which 
the tubes have been inserted and on which the pill boxes have been 
kept. By subirrigation the amount of moisture furnished can be 
kept nearly constant without interfering with the pill boxes. This 
subirrigation is best furnished by use of a large glass tube extending 
to the bottom of the sand; water poured into this will gradually per- _ 
colate through and moisten the entire surface. In most of our 
