1867.] 



Relations of Verbasra. 



159 







.4. 



6 







By calcu- 











& 





© 

 © 



lation. 









c& 



BO 





CO 





The 

 comparative 

 fertility of 

 the different 



Table 6. — Pure and Mixed Unions 



02 

 © 



© 

 DO 





© 



o g 





03 



© 



of V. blattaria, lutea, L. as $ 



o 



O ^3 



CD 



CO 



© n 



bo © 



«M O 



© 



GO 









"8 I 



O 



T © 



P 



5 



unions. 







o ^ 



d^ 



6 



> P- 



© 



6 









fe 



fc 



£ 



«3 



fe 





No. 











1. 



Yerbascum blattaria, bttea, 





















L. by own pollen, „ .. 



8 



7 



354 



50 



20 



1011 



1000 





2. 



V. blattaria, lutea by pollen 

 of V. blattaria, alba of gar- 





















dens, 



6 



3 



147 



49 



20 



980 





969.3 



3. 



V. blattaria, lutea by pollen 





















of V. thapsus, lutea, L., 



6 



4 



103 



26 



20 



515 





509.4 



4. 



V. blattaria, lutea by pollen 

 of V. tltapsus, alba of gar- 





















dens, 



6 



2 



62 



31 



20 



620 





613.2 



5. 



V. blattaria, lutea by pollen 

















. 





of V. 1/yohwitis, lutea, L., 



8 



4 



81 



20 



20 



405 





410.4 



6. 



V blattaria, lutea by pollen 

 of V. lijciaiitis, alba of gar- 





















dens, .. .. ..18 



1 



23 



23 



20 



460 



... 



454,8 



The results of experiments on the V. blattaria, varieties lutea and alba. 

 arc given in the above Tables : they comprise 12 unions between the 

 ■white and yellow varieties of three species. Let us briefly compare 

 the results of their reciprocal unions. First, the fertility of V. blattaria, 

 alba, when fertilised by its own pollen, undergoes the highly propor- 

 tionate sterilisation of 98 : 78 when fertilised with the pollen of the 

 yellow variety — V. blattaria, lutea. In the converse case, the sterilis- 

 ing influence of the cross relatively to the pure unions of these forms is 

 much decreased, the pure union of V. blattaria, lutea, yielding more 

 seed in the proportions of 90 : 88 than from its cross-union with the 

 white variety — V. blattaria, alba. Secondly, as to the hybrid unions 

 with the pollens of the yellow and white varieties of V. thapsus. In 

 these the pollen of the white variety is the more potent. Thus V. 

 blattaria, alba, fertilised by pollen of V. thapsus, alba, affords an 

 average fertility of 43, whereas by that of V. thapsus, lutea, the 

 produce is reduced to 32, relatively in both cases to 100, the average 

 fertility of V. blattaria, alba, when fertilised by its own pollen. By the 

 union of the yellow and white varieties of V. thapsus with the yellow 

 variety of V. blattaria, we see that the relative differences in the 



