18 NORTH AMERICAN FEVER TICK AND OTHER SPECIES. 
In 1906 a more extended series of experiments was instituted. In 
the first series, consisting of 59 lots deposited from February 20 to 
September 21, eggs were kept in pill boxes. As has been pointed out, 
this method accelerates incubation further than natural conditions 
are likely to. The following is a summary of the results of these 
experiments: 
Eggs deposited in March hatched in 74 days. . 
Eggs deposited in April hatched in 43 to 53 days. 
Eggs deposited in May hatched in 24 to 33 days. 
Eggs deposited in June hatched in 20 to 22 days. 
Eggs deposited in July hatched in 19 to 22 days. 
Eggs deposited in August hatched in 19 to 21 days. 
Eggs deposited in September hatched in 23 to 154 days. 
Eggs deposited October 1-7 hatched in 135 to 139 days. 
Eggs deposited October 15 and later have not hatched to date (February 20, 1907). 
In the second series of experiments relating to incubation conducted 
in 1906 a special effort was made to provide conditions that would 
give approximately the same period that must occur under normal 
conditions. (See Table II.) To do so some eggs were placed on soil 
in open-bottom glass tubes in the open air (see PI. I, fig. 2) and shaded 
for a portion of the day. Others placed under the same conditions 
were exposed to the sun at all times. In the third series the eggs 
were located in an outdoor thermometer shelter where they were pro- 
tected from sun and rain. The separate lots consisted of several 
hundred eggs. They were deposited by different females in the 
laboratory and placed together for the observations under considera- 
tion. In this way a large number of eggs deposited within the same 
24-hour period was obtained. It is supposed that these conditions 
approximate closely to those which surround the great majority of 
eggs in pastures. The following is a summary of the data contained 
in the table: 
Eggs deposited in April hatched in from 39 to 54 days. 
Eggs deposited in May hatched in from 27 to 33 days. 
Eggs deposited in June hatched in from 21 to 28 days. 
Eggs deposited in July hatched in from 22 to 26 days. 
Eggs deposited in August hatched in from 23 to 32 days. 
In September eggs deposited prior to the 18th hatched in from 23 
to 76 days. Eggs deposited after September 18 have not hatched up 
to February 20, with but two exceptions. These were eggs deposited 
October 3 and October 7, which began to hatch on February 18. 
These eggs were placed in such a way that they were more exposed to 
the sun than other lots that have not hatched, deposited before and 
since the dates mentioned. 
