Varietäten, Descendenz, Hybriden. 227 



would make them assume contamination of genes by crossbreeding 

 or any qualitative variability of genes. 



M. J. Sirks (Wageningen). 



Harris, J. A., Biometrie studies on the somatic and 

 genetic physiology of the sugar beet. (Amer. Nat. LI. 

 p. 507-512. 1917.) 



The paper contains only a summary and review of researches 

 by other araerican writers about genetics and breeding of the 

 sugar-beet. (Harris and Gortner, Harris and Hogenson, 

 Pearl and Surface, Pritchard). M. J. Sirks (Wageningen). 



Harris, J. A., Sunspots, climatic factors and plant 

 activities. (Amer. Naturalist. LI. p. 761—764. 1917.) 



The writer draws some conclusions of practical biological 

 importance from Walker's investigations of the possible relationship 

 between the number of sunspots and meteorological phenomena by 

 applying the modern methods of correlation to the problem. These 

 conclusions run as follows. 



The relationship between the number of sunspots and the 

 annual record of terrestrial metereological phenomena is very 

 slender. It is so slight that at the present time it is impossible to 

 assert on the basis of the data of any one Station alone that any 

 relationship at all exists. Thus, as far as they go, these data hold 

 out very little hope to the biologist of being able to correlate plant 

 activities with sunspot number, light intensity be the means of solar 

 influence. 



For rainfall and barometric pressure the correlations are 

 especially low. They average practically zero, but are apparently 

 on the whole negative in sign. 



The correlation between number of sunspots and terrestrial 

 temperature is the most consistent and substantial of the three. The 

 coefficients average about —.14. Thus years of larger numbers of 

 sunspots are in the long run years of lower, not higher, terrestrial 

 temperature. M. J. Sirks (Wageningen). 



Jones, D. F., Linkage in Lycopersicum. (Amer. Naturalist. LI. 

 p. 608-621. 1917.) 



From papers of previous writers the author has made up a 

 list of mendelian characters in the garden tomato, that may be 

 given here in füll : 



Number Character Dominant Recessive 



1. Fruit shape. Spherical (non con- Pyriform (constric- 



stricted). ted). 



2. Fruit shape. Roundish conic. Roundishcompres- 



sed. 



3. Loculation of ovary. Bilocular. Plurilocular. 



4. Endocarp colour. Red. Yellow. 



5. Epicarp colour. Yellow. Colourless. 



6. Fruit surface. Smooth. Pubescent. 



7. Vine habit and leaf Standard and Dwarf and rugose. 



surface. smooth. 



