RELATION OF TEMPERATURE TO DEVELOPMENT OF THE EGGS. 139 
and hatched April 25 to May 12, 1877. We will therefore select as our 
dates July 25, 1876, and April 30, 1877. 
Months. 
July 
August — 
September. 
October — 
November . 
December . 
January ... 
February . . 
March 
April 
Total . 
Number of 
days maxi- 
mum above 
50°. 
Number of 
hours each 
day. 
Product in 
hours. 
Number of 
days maxi- 
mum above 
60°. 
Number of 
hours each 
day. 
Product in 
hours. 
7 
24 
1G8 
7 
24 
168 
31 
24 
744 
31 
22 
682 
29 
22 
638 
28 
ia 
448 
25 
18 
450 
23 
11 
253 
14 
11 
154 
5 
6 
30 
7 
4 
28 
1 
4 
4 






12 
8 
96 



15 
10 
150 
7 
6 
42 
22 
12 
264 
12 
12 
144 
162 
2, 692 
115 
1,771 
It is true Professor Abbe's calculations lead him to fix upon April 30 
as the time for hatching to begin at this point, but this is upon the 
assumption the eggs are deposited about September 1, when, in fact, 
they were deposited in 1876 by the 25th of July. If we take his work- 
ing basis, that is, 1,440 hours at 60°, the hatching in this case should 
have taken place in October ; with 50° and 1,560 hours as the basis, it 
should have occurred in November. 
Another fact is revealed by comparing the results of the two places 
mentioned. Hall County and North Platte, in the same latitude, simi- 
larly situated in the same valley and not very far apart, present a wide 
difference in the number of hours required to hatch the eggs. At a 
temperature of 60°+ it required 1,228 hours in one place, and 1,771 at 
the other ; at 50°+ it required 2,012 at one place, and 2,692 at the other, 
both calculated on precisely the same basis. 
At North Platte, taking 50° as a minimum, it required 2,692 hours, 
1,771 of them 60°+, to hatch the eggs ; or, to be exact, as in the former 
case, 921 hours between 50° and 60°+ 1,411 hours between 60° and 
75°+ 36O hours above 75°. 
As a third example, we select Moorhead, in Clay County, Minnesota, 
where the eggs were deposited July 20 to August 20, 1876, and hatched 
May 15 to 30, 1877. We take, as the dates to be used, August 1, 1876, 
and May 22, 1877, and use the meteorological record of Breckenridge, 
which is in the same level valley, and but a short distance away. 
Months. 
August 
September . . 
October 
November . . 
December .. 
January 
February . . . 
March 
April 
May 
Total . 
c3 O 
gas 
a|l 
31 
28 
16 
2 


1 

19 
21 
118 
a 
8 «° 
a§£ 
I 
713 
504 
192 
16 


4 

152 
252 
1, 833 
ca o 
gas 
ja no 
a s?3 
31 
24 
7 
1 




9 
19 
91 
i o a 
11 
620 
336 
70 
6 




54 
190 
1,276- 
