290 Varietäten etc. — Physiologie, 



highest percentage of sterile spikelets, with nitrogen and phosphoric 

 acid next and nitrogen and potash last. In every instance the check 

 or untreated plots gave a lower percentage of sterile spikelets than 

 those treated with a complete fertilizer. 



There is a distinct correlation between the length of spike as 

 expressed by the number of spikelets and the number of sterile 

 spikelets. As the number of spikelets per spike increases (in other 

 words, the length of spike), the number of sterile spikelets becomes 

 greater. That is, varieties with the shorter spikes tend toward a 

 smaller number of sterile spikelets than the the varieties with the 

 longer spikes. However, the percentage of sterile spikelets per 

 spike may be greater among the varieties with shorter spikes, as is 

 shown to be the case where spikes of var3ing lengths within a 

 Single variety were examined. 



There is only a very slight correlation between the percentage 

 of sterile spikelets and the number of tillers to each plants. 



The yield of grain per plant is correlated to a fair degree with 

 a low percentage of sterile spikelets. 



The weight of the kernel or quality of grain is correlated to a 

 considerable degree with a low percentage of sterile spikelets. 



The yield of grain per spike. the length of spike, and the 

 length of culm are strongly correlated with a low percentage of 

 sterile spikelets. 



There is a slight correlation between the average number of 

 spikelets per spike and a low percentage of sterile spikelets. 



M. J. Sirks (Wageningen). 



Kylin, H., Generationswechsel und Kernphasenwechsel. 

 (Die Naturw. V. p. 84—88. 1917.) 



Was der Botaniker „Generationswechsel" nennt, will Verf. 

 als „Phasenwechsel" bezeichnet wissen. Bei den Tieren gibt es, 

 von wenigen Ausnahmen abgesehen, keinen Generationswechsel, 

 wohl aber einen cytologischen Phasenwechsel. Die Tiere sind 

 diploid, und die Reduktionsteilung erfolgt unmittelbar vor der 

 Bildung der geschlechtlichen Fortpflanzungskörper. Nach der 

 eigentlichen Reduktionsteilung findet nur eine Teilungsphase hap- 

 loider Natur statt, und man erhält als Resultat vier Spermatozoiden 

 oder ein Ei mit drei sogenannten Richtungskörpern. 



Fischer spricht von Generationswechsel im älteren Sinn und 

 Generationswechsel im neueren Sinn =r Wechsel zwischen Haplont 

 und Diplont, zwischen haploider und diploider Phase = antitheti- 

 scher Generationswechsel = Kernphasenwechsel. 



W. Herter (Berlin-Steglitz). 



Breazeale, J. F., Effect of sodium salts in water cultures 

 on the absorption of plant food by wheat seedlings. (Journ, 

 agric. Research. Washington. VII. p. 407—416. 1916.) 



The foUowing conclusions are reached at in the writers experi- 

 ments, undertaken to determine the extent to which the presence 

 of the various sodium salts commonly found in alkali soils effects 

 the absorption of plant-food elements by wheat seedlings: 



Sodium Chlorid, sodium sulphate, and sodium carbonate added 

 to nutrient Solutions in concentrations up to l.üOO p. p. m. do not 

 measurably affect the nitrogen absorbed from culture Solutions by 

 young wheat plants. 



