186 Sjjmmetry of Egg and Symmetry of Embryo in the Frog 
TABLE XXXV. 
Inclination of Sperm-radius and Egg -axis, or angle subtended at the centre of 
the egg by the distance of the sperm-entrance-point from the animal pole. 
I. ; 
close. Axes horizontal. 
II. Eggs 
spaced. 
Axes 
90—75 
5 
90—75 
27 
75—60 
9 
75—60 
23 
60— 1,5 
42 
60—43 
5. 
Jf5—80 
35 
45—30 
0 
30—15 
15 
30—15 
0 
15— 0 
15 
15— 0 
0 
Total 
123 
Total 
55 
M =40-65° M = 73-50° 
must be remembered are laid with the white hemisphere, into which the sperm 
cannot enter, on one side. While the axis lies across the slide the equator of the 
egg is parallel to its length. The mean point of entry is (Table XXXIV. a) 118° 
on one side and 114° on the other, or 28° and 24° from the equator respectively. 
This may account in part for the point of entry selected by the sperm. 
II. When the eggs are spaced and their axes vertical, the point selected by 
the spermatozoon for entrance is near the equator (Table XXXV. II.), the mean 
value is 73"50°. The eggs were white pole downwards, and the sperm-containing 
water with which they were inseminated was placed all round the eggs but did 
not cover them. This affords a sufficient explanation of what occurs. 
As we have already seen, the correlations between Sperm-entrance Meridian and 
Plane of Symmetry, between Plane of Symmetry and First Furrow, and between 
Sperm-sphere Meridian and Plane of Symmetry are all higher when "pressure" 
and "gravity" are not allowed to interfere, while that between the Sperm-entrance 
Meridian and the First Furrow is not quite as high in the absence as in the 
presence of these factors (Table XXXIII.). We might almost infer from this that 
the relations between these planes are independent of the distance of the Sperm- 
entrance from the animal pole. 
An inspection of the correlation tables (Table XXXVI.) will show how far this 
inference is justified. 
I have not calculated the coefficients, but the mean values of this angle 
(Inclination of Sperm-radius to Egg-axis) for each class of the several planes (the 
means are inserted at the bottom of the tables) will show at once that the correla- 
tion is to all intents and purposes nil (I. a, I. b, I. c), at least, when the eggs are 
close and their axes horizontal. 
The correlation is just as poor in the case of those eggs that were spaced and 
had their axes vertically placed, II. a, II. b, II. c. Where however the angle between 
the Plane of Symmetry and the First Furrow is small there is a slight lowering in 
the value of the means of the other angle (II. c). 
