M. Treviranus on the Structure of the Fruit of the Cruciferae. 365 



matter ; and the delicacy of this cellular tissue is the cause why 

 (which sometimes even occurs spontaneously, for instance mlberis) 

 the layers are so easily separable, which is impossible in those 

 cases where it has a firmer consistence, as in Thlaspi cochlear i- 

 forme, M. B. Brown first observed what he has called nerves in 

 the septum. " In some cases," he says, " the axis of the sep- 

 tum displays itself either as a single nerve or as two separate 

 parallel nerves, and from this axis tubes often pass off which have 

 the aspect and ramification of the veins of leaves and commonly 

 terminate within the border. This is most distinctly the case in 

 Farsetia. The central vessels are here very closely approximated, 

 so that they form a single cord ; they extend from the apex of the 

 septum to its base, and the veins are as numerous as unusually 

 distinct. Approximations to this structure of Farsetia, more or 

 less evident, occur in some other genera, as Parrya, Savignya 

 and Koniga. But in the last-mentioned genus, the nerve which, 

 as in all cases, arises at the apex, runs scarcely, even in the many- 

 seeded species, beyond the middle of the septum, and the far less 

 distinct veins are decurrent *." Of the plants here named I have 

 been able to examine Farsetia agyptiaca only dried, but Koniga 

 (Octadenia) maritima as well as K. {Oct ad.) lybica (if Draba num- 

 mular 7#, Eb., be the same plant) in a fresh condition. In the Far- 

 setia the septum certainly has something which looks very like a 

 central nerve, about as it is represented by Desfontainesf,andI ob- 

 serve the same condition of the part in Octadenia maritima , except 

 that the veins running out to the side have a somewhat different, 

 that is, a curved course. In Oct. lybica each mid-nerve descends to 

 about opposite the insertion of the ovule on the border ; but rami- 

 fications go from it to all sides and are distributed over the whole 

 of the septum; they form an intricate network by their regular 

 anastomoses, and are often distinguishable by a reddish colour. In 

 Cochlearia anglica also, likewise in Vesicaria grandijlora and V. 

 gracilis, B.M., a nerve may be observed in the septum descending 

 from the style. In Cochlearia it loses itself in the lowest parts of the 

 septum where the funiculi arise, but in the two Vesicarias it only 

 goes to the middle, and by no means gives off branches, but after 

 becoming gradually attenuated suddenly terminates. In all these 

 cases it was evident that the said nerve took its origin where the 

 style ended, appearing to be an immediate prolongation of the 

 central substance of that organ ; it reached also either only to the 

 middle or beyond the middle, but never to the base of the sep- 

 tum. Dr. C. A. Meyer, in his important work on the Cruciferse of 

 Altai J, has devoted particular attention to the septum and found 



* L. c. 13, 14. t Fl. Atlant. ii. t. 160, f. 6. 



X Ledebour, Fl. Alt. iii. 1-219. 



