252 Mendel's Laws of Alternative Inheritance in Peas 
been offered, especially by De Vries (32) and by Tschermak (29) for other plants, 
but these seem as little likely to prove generally valid as Mendel's formula itself. 
The fundamental mistake which vitiates all work based upon Mendel's method 
is the neglect of ancestry, and the attempt to regard the whole effect upon 
offspring, produced by a particular parent, as due to the existence in the parent of 
particular structural characters ; while the contradictory results obtained by those 
who have observed the offspring of parents apparently identical in certain 
characters show clearly enough that not only the parents themselves, but their 
race, that is their ancestry, must be taken into account before the result of pairing 
them can be predicted. 
ALPHABETICAL LIST OF AUTHORS CITED. 
1. Bateson, W. On Progress in the Study of Variation. Science Progress, N. S., Vol. I. 
No. 5 (1897) and Vol. ii. No. 6 (1898). 
2. Clarke, Trevor. Report of Proceedings : International Horticultural Exhibition and 
Botanical Congress, London, 1866, p. 143. 
3. CoRRENS, C. G. Mendel's Regeln liber da.s Verhalten der Nachkommenschaft der Rassen- 
bastarde. Berichte d. deutsch. botan. Gesellsch. xviii (1900), pp. 158 — 168. 
4. . Summary in Botanische Zeitschrift, Abth. ii, 1900. 
5. . Ueber Levkojenbastarde. Botan. Centralbl. lxxxiv (1900), pp. 97 — 113. 
6. . Ueber Bastarde zwischen Rassen von Zea Mays. Ber. d. deutsch. botan. Gesellsch. 
xrx (1900), pp. 211—220. 
7. . Bibliotheca Botanica, No. 53 (1901). 
8. Crampe. Zuchtversuche mit zahmen Wanderratten. An elaborate series of papers in 
Landwirthschaftliche Jahrbucher, vi (1877), xii (1883), xiii (1884), xiv (1885). The 
chief results quoted in the text are in the paper of 1877 ; but the whole series should 
be referred to. 
9. Darwin, C. The Variation of Animals and Plants under Domestication (quoted from 
2nd Edition, London, 1875). 
10. Fischer, von. litis (Mustela Putorius) und Frett {31. furo). Der Zoologische Garten xiv 
(1873), pp. 108—112. 
11. . Beobachtungen liber Kreuzungen verschiedener Farbenspielarten innerhalb einer 
Species. Der Zoologische Garten xv (1874), i>p. 361 — 374. 
12. Gartner, C. F. von. Versuche und Beobachtungen liber die Bastarderzeugung im Pflanzen- 
reich. Stuttgart, 1849. 
13. Galton, F. The Average Contribution of each several Ancestor to the total Heritage 
of the Offspring. Roy. Soc. Proc. Lxi (1897), pp. 401—413. 
14. Giltay, E. Ueb. d. directen Einfluss d. Pollens auf Frucht- und Samenbildung. Jahrb. 
f. wiss. Botanik xxv (1893). 
