IN THE TROPICS. 
387 
Thus by the examination of their seeds in F 3 the constitution of 
the 72 F 2 plants for which a summary follows could be determined, 
as well as that of four of the offspring of the exceptional cross No. 
215. Twenty other plants gave too poor a crop to allow of this 
being done :— 
Mendelian Constitution of Parents. 
■ 
Parent Seed. 
AaBb. 
AaB. 
AaB. 
ABb. 
aBb. 
AB. 
Ab. 
Ab. 
ab. 
Total. 
Sm. y. 
15 
7 
(1) 
5 
4 ! 
(1) 
33 
Sm. g. 
— 
— 
12 
— j 
- — 
— 
5 
— 
— 
17 
Wr. y. 
— 
— 
— ■ 
— 
12 
— 
— 
3 
— 
15 
Wr. g. 
— 
— 
—i 
Sp 
! 
— 
(1) 
— 
6 
7 
Total 
15 
7 
13 
5 
1 “ 
4 
7 
4 
7 
72 
The figures are not sufficient for testing the distribution according 
to Mendel’s law with any exactness, though so far as they go the 
agreement is clear enough. They do afford however a test of the 
accuracy of the sampling. 
There are apparently three errors among the 72 cases, namely :— 
{a) 1 seed sown as sm. y. gave rise to sm. and wr. green 
only. 
(b) 1 seed sown as sm. y. gave rise to wrinkled yellow 
only. 
(c) 1 seed sown as wr. g. gave rise to smooth green 
only. 
(b) and (c) illustrate the fact already stated that smooth and 
wrinkled seeds are not always to be distinguished with certainty 
from their external appearance, (a) may be due to the inheritance 
of the property of turning yellow as the result of exposure. Taking 
into consideration the sources of error and the poverty of the crop, 
the sampling may be said to have been carried out with a fair degree 
of accuracy. The error is not sufficient to affect the general conform¬ 
ity with Mendelian expectation. 
