1867.] 



Relations of Verbaaca. 



153 



former are also susceptible of fertilisation by the male element of V. 

 nigrum. The full explanation of these curious and complicated sexual 

 relations, I leave for more sagacious and ingenious investigators, and 

 simply conliiie myself to remarking on the apparent support that these 

 and more especially those other cases which I have communicated to 

 the Linnean Society,* on the fertilisation of certain species of Passiflorae, 

 — in which I showed that individual plants perfectly self-sterile readily 

 effected reciprocal unions with other similarly characterised individuals 

 of the same species — give to that view which Mr. Darwin has propounded 

 regarding the existence of a law in nature necessitating " an occasional 

 cross with another individual, or, that no hermaphrodite fertilises itself 

 for a perpetuity of generations," but " that some unknown great good 

 is derived from the union of individuals which have been kept distinct 

 for many generations. "f 



In the following table, the results of the pure unions of V. 

 phceniceum given on the first line are taken from capsules on a 

 specimen in the Edinburgh University Herbarium, as I have not yet 

 been successful in getting good capsules from any of the plants which I 

 have had an opportunity to experiment upon by their own pollen. The 

 other plants of V. phceniceum and varieties mentioned in the table are the 

 same as those from which I had the results given in Table 1. Indeed, 

 in one or two instances, the same experiments are re-stated, with a 

 view to show more clearly the relative degrees of sterility resulting 

 from the crossing of undoubted varieties of a species on the one hand, 

 with those from the hybridisation of distinct species on the other. 



Table 2. — Pure and Mixed Unions 

 of Verbascvm phceniceum and 



+3 



s 



> 







GO 

 O 



m 



6 



By calcu- 

 lation. 



The 

 comparative 

 fertility of 







var. as $ 



6 ^ 



o § 



6 



© C3 

 g U 



< 



6 » 



O 



02 



O 

 6 



the different 



uuiuns. 



No. 







1. Verhascum phceniceum L. 



















(wild plant naturally ferti- 

 lised), 



•• 



4 



142 



36 



20 



710 



1000 





* "Journal Linn. Soc." Vol. 8. p. 197. 



f Orchid Fertilisation, pp. 1—360, 

 20 



