1867.] 



Relations of Verbasm. 



155 



by a similar comparative study of the relative fertility of tlie pure 

 unions of V. plmmiceum and the different hybrid unions given in the 

 Table, we find that the highest degree of fertility results from the union 

 of V.ferrugineum (which perhaps is correctly regarded by De Candolle 

 and others as a mere variety of V. pliceniceuni) with V. phceniceum, the 

 proportions of the pure to the hybrid unions being as 100 : 59, in 

 favour of the former. The lowest degree of fertility results from the 

 unions of V. ovalifolium^ with V. phoeniceitm, the proportion of the 

 pure to the hybrid-unions in this case being as 100 : 24.) Lastly 

 the average fertility of the five hybrid unions given in the latter lines 

 of the Table, relatively to the pure unions of V. jihoeniceum, is nearly 

 as 100 : 40, or as 2.5 seeds of the pure unions to one of the hybrid 

 unions. Thus, the relative differences in the degree of sterilisation 

 resulting from the hybridisation of distinct species, and that from the 

 cross -impregnation of varieties of a species, relatively in either case to 

 the pure unions, is in the former as 2.5 : 1, and in the latter as 4 : 3. 







■^ 



6 





3 



By calcu- 









CD 



Ph 





CD 



CD 



lation. 







jE 3. — Pure and Mixed Unions 





GO 



CD 

 ~0 





CD 







The 



Tabi 







comparative 



of 



V. lychnitis, L. var. alba 



1 ' 



CO 



03 



w IB 

 P. 



CD o3 

 bD « 

 oS -_, 





CD 



fertility of 



as 



$• 



o 

 td . 



o t> 

 w 



6 ^ 



0?- 



CD 

 Oi 



o 

 6 





CD 

 03 



O 



d 



the different 

 unions. 







fc 



K 



5 



<4 



o 



£ 





No. 





















1. 



Verbascum lychnitis, var. 

 alba of gardens, by own 





















pollen, 



6 



6 



250 



42 



20 



833 



1000 





2. 



V. lychnitis, alba, by pollen 

















<, 





of V. lyclmitis, lutea, L., 



8 



8 



274 



34 



20 



685 



.. 



822.3 



3. 



V. lychnitis, alba, by pollen 

 of V. thapsus, L. var. alba, 





















of gardens, 



10 



5 



98 



20 



20 



392 



-0 



470.5 



4. 



V. lychnitis, alba, by pollen 

 of V. phceniceum, L. var. 





















alba of gardens, 



5 



4 



113 



28 



20 



565 





678.2 



