400 KARL B. KRISTOFFERSON 

or are not the results of complicated segregations combined with coup- 
ling, in conformity with HERIBERT-NiLsson’s (1916) theory. 
With regard to practical breeding, it should be said, that spon- 
taneous crossings as a rule have only a small disturbing effect, and 
no change should be made in the usual methods employed in the case 
of autogamous plants. 
The fact of spontaneous crossing, no doubt, may be of certain im- 
portance for the seed-cultivation of the beans. If the seeds are not 
well sorted before the sowing a variety will soon degenerate owing to 
crossings with other varieties cultivated side by side, as often is the 
case. Indeed, it is a question whether or not such a variety as the cho- 
colate brown bean, which in two years has given more than 4 % of 
bastards, should be cultivated close to other varieties. 
Since the above was written (Oct. 1920) investigations on the 
same subject have been published by Lenz (1921 a and b) and 
SCHIEMANN (1921). Their investigations have not been made on 
material sown for this special purpose. The percentage of crossings, 
however, is about the same as in my trials. 
My assumption stated in the beginning of this paper that nobody 
has made attempts to ascertain the percentage of crossing by way of 
experiments is wrong. SCHIEMANN states in her paper that Mayer- - 
GMELIN and Emerson have made such trials. Their results seem 
to be about the same as mine. 
LITERATURE CITED. 
1. Emerson, R. A. 1916. A genetic study of plant height in Phaseolus vulgaris. 
Bull. Agr. Exper. Sta. Nebr. 1916. 
2. FRUWIRTH, C. 1910. Die Züchtung der landwirtschaftlichen Kulturpflanzen. 
Bd. 3. 
3. HERIBERT-NILSSON, N. 1916. Eine mendelsche Erklärung der Verlustmutanten. 
Ber. Deutsch. Bot. Ges. 1916. 
4. Lenz, F. 1921 a. Über spontane Fremdbefruchtung bei Bohnen. Zschr. ind. 
Abst. Bd. 25. 
5. — 1921b. Zur weiteren Fragestellung über die Befruchtungsart der Bohnen. 
Ibid. 
6. SCHIEMANN, E. 1921. Fremd- und Selbstbefruchtung bei Bohnen nach Aus- 
leseversuchen. Ibid. 
