THE LEAF. 



215 



(PI. XIX, fig. 3d), the sunflower (Helianthus annuus), 

 the black bindweed (Polygonum Convolvulus), and the 

 wild radish (Baphanus Baphani strum) (PI. XIX, fig. 

 oe) ; Mr. Dymes has seen cases in the water-milfoil 

 (Myriophylluin spicatum), the fringed buck-bean 

 (Limnanthemum nymphseoides), and the brookweed 

 (Samolus Valerandi); the present writer has seen it in 

 Gaillardia, Eremostachys laciuiata (PL XIX. fig. 3a), 

 Salvia amplexicaidis (PI. XIX, fig. 3c), Ammi Visnaga, 

 Brassica sp., and others. It is thus clearly a very 

 common and widely distributed phenomenon. It may 

 assume three different forms. The two cotyledons 

 may fuse by their margins of one side only and assume 

 an apparently lateral position opposed to the first- 

 formed plumular leaf, as in Salvia and Mercurialis, or, 

 the mode of fusion being the same, the double organ 

 so formed may occupy a terminal position on the axis, 

 as in Eremodaclbys ; or, again, the cotyledons may fuse 

 by both margins and form a cup-, salver-shaped, or 

 tubular structure surrounding the plumule.* 



There are many plants which normally develop a 

 single cotyledon, e. g. the lesser celandine (Banumulus 

 Ficaria), Anemone apennina, Fiugutada grandiflora and 

 P. vulgaris, and Cyclamen persicum; in all these the 

 cotyledon is formed in the same way as in the abnormal 

 cases above cited. The single terminal cotyledon 

 normally formed in such cases as Corydalis solida and 

 Abronia is due to suppression of the other one. 



2. Schizocotyly. — Another phenomenon, about 

 equally common, consists, in the tendency to multiply 

 the cotyledons, which is, of course, the reverse hap- 

 pening to that just considered. The forking of one 

 or both" cotyledons is merely the first stage in the 

 formation of three or four instead of the normal two. 

 The sycamore (Acer Pseudo-platamts) very often has 

 three or four cotyledons in its seedlings (PL XIX, fig. 

 4). The writer has seen interesting cases in the wall- 

 flower (Cheiranthus Cheiri); in one seedling there were 



* " Amphicotyly." 



