ate 
ae 
-1907.] Wrinkled Peas, and thew resultant Starch-grains. 135 
fig. 1) and the type of grain of the wrinkled pea (the compound or c-grain— 
fig. 2), in respect of three characters— 
(a) It is intermediate in shape as measured by its length-breadth index— 
that of the p-grain being 66, that of the c-grain 92, and that of the 
r-orain 85 (neglecting decimals). 
(6) It is intermediate in the distribution of compoundness, inasmuch as 
some of the 7-grains are compound and some single. 
(c) It is intermediate in the degree of compoundness, inasmuch as amongst 
those r-grains which are compound the most usual number of 
constituent pieces is three, whereas in ¢-grains it is Six. 
2. In a subsequent generation—F;—the homozygote round peas contain 
p-grains; the heterozygote round peas contain r- or intermediate grains. But 
both r- and intermediate grains may be associated either with a high, or with 
a low degree of compoundness. 
3. P-grains occasionally occur in wrinkled peas in F;, and the evidence 
(Table IV, 54.97 and 187) suggests that the existence of these grains in 
wrinkled peas tends to make them less wrinkled. 
4, A wrinkled pea takes up more water when it germinates than a round 
one. The hybrid between a round and a wrinkled pea is intermediate in 
respect of this character between its two parents. . 
5. But this intermediateness of the hybrid in absorptive capacity is not 
occasioned by the intermediateness of the starch-grain of the hybrid, because, 
in F,, peas containing r-grains and peas containing p-grains both have the 
same absorptive capacity as the F, pea (see Table V). 
6. When, therefore, we cross a round with a wrinkled pea, we are dealing 
with four separately heritable characters :— 
.(i) The shape of the pea—whether round or wrinkled. 
(11) The absorptive capacity of the pea—whether low or high. 
(iil) The shape of the starch-grain—whether long or round. 
(iv) The constitution of the starch-grain—whether single or compound. 
REFERENCES. 
Mendel, G. J. “Versuche iiber Pflanzen-Hybriden,” ‘ Verhandl. d. Naturf. Vereines in 
Briinn,’ vol. 4, 1865. 
Weldon, W. F. R. “ Mendel’s Laws of Alternative Inheritance in Peas,” ‘ Biometrika,’ 
vol. 1, p. 231, 1901. 
Gregory, R. P. “The Seed Characters of Piswm sativum,” ‘New Phytologist,’ vol. 2, 
No. 10, 1903. 
VOL. LXXX.—B, L 
