178 Symmetry of Egg and Symmetry of Embryo in the Frog 
ously for eggs under the same conditions (Table VI., IV. a), when a was 34'46° + 1'07. 
The difference is evidently due to the absence in the present case of any angles 
over 75°, but I can suggest no reason for this. 
(2) The Sperm-entrance Meridian and the First Furrow. (Tables XXVI. 6, 
XXVII. h, XXIX. h, XXX. h.) 
TABLE XXVIII. 
Sperm-sphere Meridian. 
I. Eggs close. 
Axes horizontal 
II. Eggs spaced. Axes vertical 
Angle 
b. Sperm-spliere 
c. Sperm-sphere 
b. Sperm-sphere 
c. Sperm-sphere 
Meridian and 
Meridian and 
Meridian aud 
Meridian and 
First Furrow 
Plane of Symmetry 
First Farrow 
Plane of Symmetry 
- 90°— 75° 
3 
3 
0 
2 
75 —60 
3 
2 
1 
0 
60 —Jt5 
5 
5 
1 
2 
Jf5 —30 
8 
9 
3 
6 
30 —15 
12 
12 
15 
5 
15-0 
32 
26 
11 
8 
+ 0 —15 
28 
17 
8 
13 
15 -^30 
10 
12 
9 
9 
30 —45 
8 
11 
3 
6 
4S —60 
2 
7 
0 
3 
60 —75 
6 
3 
1 
0 
75 —90 
3 
13 
3 
1 
Totals 
120 
120 
55 
55 
M 
14-00° ±2-10 
9-37°±2-51 
14-33°±2-85 
1-77° ±2-98 
34 -19° ±1-48 
40-73° ±1-77 
31 -31° ±2-02 
32-8r±2-ll 
It is quite clear that the tendency for the First Furrow to include the point of 
entrance of the spermatozoon is very great, whether the eggs be under the influence 
of gravity and pressure or not. It is difficult indeed to determine whether these 
external conditions exert an unfavourable influence upon the value of the relation 
or not, since, where the standard deviation is less when both factors are omitted 
(o- = 21-02° + 1-35 as compared with cr = 30"65° + 1'32), the correlation is not greater 
as we should expect but less (p = '435° + "074 as compared with p = "613° + •038). 
In comparing these two correlation tables (XXIX. b and XXX. 6) it will be seen 
at once that in the first case the coefficient is increased by the presence of high 
frequencies in the positive corners of the table (all examples of precisely 90°, I 
should say, have been halved), that is, of instances in which the Plane of Symmetry 
