Varietäten etc. — Physiologie. 329 



exists in the properties of the sap of the leaf tissue of the two types 

 of leaves. M. J. Sirks (Wageningen). 



Harris, F. S. and J. G. Hogenson. Some correlations in suj- 

 gar beets. (Genetics. I. p. 334—347. 1916.) 



The writers publish some tables that show the following corre- 

 lations of characters in sugar beets: 



1. Weight of beet with percentage sugar = — .2878 + .0074. 



2. Percentage sugar in the mother beet with quantity of seed 

 produced = .0049 + .0143. 



3. Height of plants with weight of seed produced — .39S5 + .0128. 



4. Weight of mother with quantity ofseed produced = .3075 + 0.131. 



5. Xumber of stems on each plant with the quantity of seed 

 produced — .2771 + 0.133. 



6. Number of days to mature with quantity of seed produced 



— .1954 ± 0.156. 



7. Number of leaves on each stalk with quantity of seed pro- 

 duced = .1217 + .0143. 



8. Days to mature with leight of plant = .1748 + .0163. 



9. Percentage of sucrose in mother with days to mature seeds 



— .1292 ± .0155. 



10. Percentage of sucrose in mother beet with member of leaves 

 on each stalk = .2484 ± .0134. M. J. Sirks (Wageningen). 



Copeland, E. B., Growth phenomena of Dioscorea. (Philipp. 

 Journ. Sc. C. ßotany. XI. 5. p. 227—241. 1916.) 



At the end of his paper, the writer publishes the following 

 summary: 



Previous observations, that a nutation of shoots of Dioscorea 

 ceases in darkness, are in general correct. Especially active stems 

 may nutate and twine around a support in darkness. 



Prof. Newcombe's Observation that the failure to twine in 

 darkness is due to changes a number of centimeters from the apex 

 is correct. 



The rate of growth of vigorous young shoots is but slightly, if 

 at all, influenced by the illumination. 



The elongating region is much shorter in darkness than in 

 light. The part of the stem which executes the movements, in active 

 nutation in light, almost, or quite, ceases to elongate in darkness, 

 and it is for this reason, that twining ceases in darkness. 



The short elongating region in etiolated shoots ma3 r be explained 

 biologically as a selected adaptation to the condition under which 

 young shoots in nature are most likely to find themselves in dark- 

 ness — this is, in the soil, where a long growing region would be 

 just as dangerous as the production of ample leaves. 



The growing shoots of Dioscorea are excellent material for the 

 analysis of the infiuence of temperature or other external conditions 

 upon growth, into: A, effect on the growing region; B, effect on 

 the metabolic processes, which make food available; and C, trans- 

 location of food to the growing region. Low temperatures, applied 

 either to the food störe, or to the stem through which the food 

 must pass to the growing region, result in prompt checking of 

 growth. 



It is suggested that the blasting of the growing point and its 



