310 
(hi the Xe.^t and Eggs of the Common Teni 
and with our numbers e'- = •0832, leading to 6 = '9576a — an improbable but not so 
impossible a relation as the former. It could hardly, however, escape observation, as 
even slightly distorted eggs are easily recognised. It seems, therefore, probable that 
the exaggeration of the girth in the transverse sense is due to the difficulty of 
adjusting the tape to the true maximum transverse section — the temptation 
being to bring the reading edge of tlie tape into contact with itself tvitli the scale 
facing outwards. If we suppose the celluloid scales to be 0*5 mm. thick this 
would account for the deviation. Probably the longitudinal girth is exaggerated 
in like manner. 
Unfortunately it did not apparently seem possible for the fieldworkers to adopt 
a more elal)orate system of classification for the mottling than was used in 1913 
and accordingly no further light is obtainable with regard to the difficulties 
suggested on p. 146 of the first paper. 
The question of possible pressure on the surface of the egg as it passes through 
the oviduct influencing the amount of pigment deposited was again investigated 
by considering the broader egg in each pair from the same clutch (see I.e. p. 146). 
The broader egg in every possible clutch pair has : 
Greater mottling in 189 cases More dense ground colour in 223 cases 
The same „ „ 312 „ The same „ „ „ 290 „ 
Less „ „ 234 „ Less dense „ „ „ 224 „ 
Thus our 735 pairs confirm the previous result (on about lOU pairs) as far as the 
mottling is concerned, but not the density of ground colour. There is no dis- 
tinction in ground colour on the average between eggs of different breadths from 
the same hen, but the broader egg does appear to have less marked mottling. 
We shall consider later whether this I'esult for eggs of the same clutch holds for 
the general population. 
(2) Change of Type of Egg ivith Season. . 
We have : 
TABLE I. 
Character 
Mean 
Season 1913 
Season 1914 
Length L ... 
Breadth B 
Longitudinal Girth G, 
Transverse Girth Gi 
Index 100 B/L 
Index of Ovality 0 
4-14+ -007 
2-98 + -004 
11 -39 ±-01 5 
9-59 + -014 
72-04+ 136 
56-35 + -171 
4-21 + -004 
3-01 ± -002 
1 1 -56 + -007 
9-66 ± -006 
71-75 + -070 
55-81 ±-088 
1 
It is clear from this table that the eggs of 1914 were significantly lai'ger than 
those of 1913. As the fieldworkers remarked before the eggs were tabled and 
