THE PRINCIPLE OF COHESION. 



77 



features when tliej first cease to fee axial and become appen- 

 dicular. The accompanying diagrams (Fig. 19), (a) Lysi- 

 macliia nemorum and (^h) Primula veris, will illustrate these 



a. 



Fig. 19. — a, Lysimachia nemorum ; b, Primula veris. 



remarks. The sections are taken on planes * where the 

 pistil is emerging from the receptacle ; s. represents the 

 sepaline cords ; ah. st. abortive stamina! cords ; jj. the petal- 

 ine and staminal (combined) ; d.c. dorsal carj^ellarj ; pi. c. 

 placentary cords. 



A free central placenta may result from the destruction 

 of the septa of an originally axile placenta, as occurs in the 

 Caryophyllece. Thus, the ten rows of ovules in Lychnis 

 sufficiently indicated their marginal origin. I may add that 

 a careful investigation into the origin and distribution of the 

 cords has convinced me that the axis in flowers of the 

 CaryopTiyllece early ceases to take any part in the structure 

 of the pistil. 



* Fig. a represents a section taken rather lower down than in Fig. h ,• 

 as the cords in the latter are still undiiferentiated in Fig. a. 



