268 OBSERVATIONS ON PLANTS 



The third point of agreement is the adhesion of the 

 funicuU imibihcales to the septum. This adhesion, though 

 really existing, is not very obvious in the monospermous 

 cells of Koniga maritima ; but in the supposed variety of 

 this species from TenerifFe, in which the cells are occasion- 

 ally dispermous, it is manifest, and is very remarkable in 

 all states of Koniga libyca. 



I first introduced this adhesion of the fanicnli to the 

 septum as a generic character in distinguishing Petrocallis 

 from Draba. It has since been advantageously employed 

 in the character of Lunaria by M. De Candolle, who, how- 

 ever, supposes this structure of much rarer occurrence in 

 210] Cruciferoe than it really is. According to my observations, 

 it is neither unfrequent, nor always of generic importance. 

 Thus, I find it to exist in some species only of Arabis, 

 namely A. Turrita, pendula, and canadensis, and hence I 

 did not introduce it into my generic character of Parrya, 

 though I have noticed it in my description of the species. 



The principal difference existing between these t\v'o 

 species of Koniga is that the cells of the ovarium and 

 silicula of K. maritima are monospermous, while those of 

 Jibyca are polyspermous, the number being variable, appa- 

 rently indefinite, but not exceeding six. There are, how- 

 ever, other instances in this family, in wdiich the mere dif- 

 ference betw^een definite and indefinite number of seeds is 

 of specific importance only, as in Draba and Meniocus, in 

 each of which a species exists with dispermous cells ; and 

 the objection arising from the apparently still greater dif- 

 ference between unity and indefinite number in the two 

 species of Koniga is removed by a supposed third species 

 or variety of K. maritima, in wdiich two seeds are occasion- 

 ally produced in each cell. It may even be observed that 

 from unity to the indefinite number in this case, where the 

 ovula in the different cells are alternate, the transition is 

 perhaps more easy than from the binary to the indefinite, 

 in cases where, as in Alyssum properly so called, the ovula 

 are placed opposite in the different cells, and are in the 

 same cell equidistant from its apex ; this symmetry, pro- 

 bably, admitting of addition only by fours. 



