34 Varietäten etc. — Physiologie. 



but more closely resembles the cultivated parent. It does not 

 .shatter. The base of the upper grain is like the cultivated parent. 



Data are available from 465 F.>-plants. Of these about 70 have 

 been grown in an Fg-generation. These data show that the wild 

 parents carr}'' genes for gray and probably for yellow color in 

 addition to the black. These three colors segregale independently 

 of each other. The observed ratio closely approximates the expected 

 and confirms Nilsson-Ehle's conclusions. 



The cultivated base of the grain is dominant to the wild and 

 segregates independently of the color genes. The heterozygous 

 condition in the lower grain can be recognized in the majority of 

 plants. In this cross seven pairs of characters are completely corre- 

 lated with the character of the base. The characters associated with 

 the wild base are 1) heavy awn on the lower grain, 2) awns on 

 the Upper grain, 3) wild base on the upper grain, 4) pubescence 

 on the pedicel on the lower and 5) on the upper grain, 6) pubes- 

 cence on al sides of the base of the lower grain and 7) pubescence 

 on the base of the grain. There is no evidence in present cross 

 to indicate whether these characters are due to the action of a 

 Single pair of genes or to several pairs completely linked. Evidence 

 from certain other crosses, as yet not completely analj-zed, indicates 

 the existence of separate genes for some of these characters. 



The gene for pubescence on the back of the lower grain is 

 partiaily linked with the black color factor. The Fg-generation is 

 too small to determine the exact degree of linkage but indicates 

 that there are about 0.7 percent of crossovers. The gene for 

 pubescence on the back of the upper grain segregates indepen- 

 dently of the color factor except that in the abscnce of the gene 

 for pubescence on the lower grain the gene for pubescence on the 

 upper grain is unable to act. In this sense the gene for pubescence 

 on the lower grain is a basic pubescence factor similar to the color 

 factor (C) found in many animals and plants. 



However this gene for pubescence on the back of the upper 

 grain is linked with the wild base. The percent of crossovers indi- 

 cated by the present data is about 1,5. 



The observed and expected results in the F^-generation when 

 both sets of partiaily linked genes are considered, are given in a 

 table. M. J. Sirks (Wageningen; 



Tottingham, W. E. und A. J. Beck. Antagonism between 

 manganese and iron in the growth ofwheat. (Plant World. 

 XIX. p. 359-370. 2 fig. 1916.) 



Weizenwasserkulturen erhielten zu der Knop'schen Lösung (mit 



Monokaliumphosphat unter Ausschluss von Eisenphosphat; in 2 Kon- 



1 N N i 



zentrationen j^^r^ und j die Salze FeClo und MnCU. Nach 



3 Wochen wurden die Pflänzchen herausgenommen, mass man die 

 Wurzeln und nach ihrer Abtrennung wurden sie bei 98° C getrocknet 

 und gewogen. 



I. Es ergab sich bezüglich des Wurzelsystems: MnClg ist 

 selbst in geringer Dosis schädlich und macht die positiven Wir 

 kungen des FeClg ganz nichtig. In stärkeren Konzentrationen haben 

 beide Salze eine giftige Wirkung, das FeClg hemmt die Wirkungen 

 des MnCl.^. 



IL Bezüglich der oberirdischen Teile: MnCl, regt in go 



