WHITE AND YELLOW YOLK OF OVA 459 
ovary which were grown at different periods. It has been 
shown moreover by the Sudan-method that the rate of growth 
may be reduced not only to one-half that given above, but to 
absolute zero; this, however, is only a confirmation of what in- 
ference has long declared must be so, since ova may even de- 
crease in size while in the ovary, 7. e., they may be resorbed. 
TABLE 1 
Showing under section A the rate of growth of hens’ eggs as this was measured in 
central and peripheral parts of the yolk by means of Sudan. The numbers in the 
first column refer to the number which this egg bears in the plate. In section B 
are recorded measurements of the thickness of pairs of white and yellow yolk 
strata in central and peripheral regions of the ovum as this could be seen with 
unaided eye or with addition of iodine solution. The seven measurements here 
chosen arbitrarily from nearly forty in the records, are consecutive measure- 
ments of eggs from different hens. 
A B 
24 HOURS RADIAL GROWIH THICKNESS OF A PAIR OF 
IN MM. YOLK STRATA 
NO. OF EGG 5 = ‘eens: va NO. OF OVARY pA IS 7 & 
Central | Peripheral Central | Peripheral 
i Jel, il iD, te Jel; al 1G 
at 1 1.41 1 16 2.16 
4° 1 13) 1 '7/ 2 1.54 1.54 
a 1 Laz 3 Wea) 
(aq 1 1.64 + 2.5 225 
1 2 1.8 1.8 5 1.4 1.4 
2 2 lg | W.&: 6 2.0 2.0 
5 2 | 1108) 7 levy gga 1.47 
ANCTAR CS 3 ogi 1.53 1.67 | Average...... | 1.85 18 
2. Ova of less that 6.0 mm. in diameter 
It has not been possible to obtain a deposit of Sudan in eggs 
smaller than 6.0 mm. in diameter. This failure is explained by 
the fact that these ova are growing very slowly, as compared 
with the more advanced ova, and the intake of the stained food 
is here not rapid enough to give a perceptible effect. We shall 
see, moreover, that this white yolk—for ova of this size are com- 
