184 Sjfmmetnj of Egg and Symmetry of Embryo in the Frog 
la Table XXVIII. I. c and II, c will be found the distributions, and the corre- 
lations in Table XXXI. a and h. 
When the eggs are close and their axes are horizontal the standard deviation 
is high, (r = 40'73° + 1"77, and practically as high as that found in the case of 
Sperm-entrance and Plane of Symmetry (Table XXVI. c). The correlation is 
negligible. 
When, however, the eggs are spaced and their axes vertical the standard devia- 
tion is lower, the correlation coefficient higher, cr = 32-81° + 2-11, p = -188 ± -088. 
Judged by both constants the relation of the Sperm-sphere Meridian to the Plane 
of Symmetry is less than that between the latter and the Sperm-entrance. There 
is however some slight connection between the two. 
(6) The position, on the slide, of the point of entrance of the spermatozoon, or 
the relation of this point to (a) the direction of 'pressure,' parallel to the length 
of the slide, and (/3) the direction, across the slide, of the gravitation plane of 
symmetry. 
When the eggs are spaced and the axes horizontal, the spermatozoon enters at 
any point at random, as may be gathered from the frequency polygon in Fig. 6 II. 
(p. 159, above.) 
When however the eggs compress one another in the longitudinal rows, the 
axes being horizontal, the spermatozoon enters mainly on those sides of the 
eggs which are in contact, as is evident from Table XXXIV. and Fig. 6 I. The 
frequencies are much higher about 90° than elsewhere. Further, while a few 
eggs may be found in which the sperm has entered about 180°, hardly a single one 
has entered about 0°. 
It was towards this side that the white pole was turned up, and, as is known, 
the sperm does not enter in the vegetative hemisphere. 
These values have been determined from the known value, in each egg, of the 
angle between the entrance point and the First Furrow, and by subtraction of the 
angle between Sperm-entrance and Plane of Symmetry. The position of the latter 
on the slide is known, and hence the point of entrance of the sperm. On the 
assumption that this point is opposite to the grey-crescent, angles may be distin- 
guished from their supplements, a distinction which could not otherwise be made 
since what is actually measured is the angle between Sperm-entrance and First 
Furrow after the eggs have been removed from the slide. This assumption may 
or may not be justified. It might be better therefore to ignore the distinction 
and tabulate the frequencies as in Table XXXIV. h, where the distribution is 
about 90°. It may be worth while to point out that the standard deviation of this 
distribution (<T = 44f'13° + 1*87) is nearly the same as those of the distributions of 
the First Furrow given in Table XIV., I. A and II. A. 
