76 JOUKNAL OF THE ROYAL HOETICULTURAL SOCIETY. 
not become more and more fixed — in other words, tend gradually to pass 
over from the group which we term adaptational to that which we term 
ancestral. This is, I would suggest, probable, though it would un- 
doubtedly require a long-contmued series of experiments to demon- 
strate it. 
APPENDIX. 
Classification of Angiosperms, according to Eichler's Natiirlichen 
Pflanzcnfamilien (1892-6), showing the independent origin of the 
aquatic habit in a comparatively small number of cohorts. 
Class L — Monocotyledones. 
Cohort 1. Pandanales. Typha, Sparganium. 
„ 2. Helobiese. Almost entirely aquatic. Fotamogeto7iacc(Ey 
NaiadacecB, Apojiogetonacece, JuncaginacecB, Alis- 
macecB, Butomacece, HydrocliaritacecB. 
„ 3. Glumiflorge. Few aquatics, such as G/?/cm<2yZzwtos and 
Scirims lacustris. 
„ 4. Principes. Palms. 
,, 5. Synanthae. Cyclanthaceae. 
„ 6. Spathiflorse. Arace^e, including Acorus, Pistia, Orontium. . 
Lemnacece. 
,, 7. Farinosae. Pontederiacece. 
,, 8. liliiflorae. Juncus. 
,, 9. Scitaminese. ) -d i.- 
' ^ -Tr. ^ 0 ^ Few, if any, aquatics. 
,, 10. Microspermae. Orchids, &c. j ^ 
Class II. — Dicotyledones. 
Series 1. — Aechichlamyde^ — 
Cohort 1. Piperales. 
„ 2. Juglandales. 
,, 3. Salicales. 
i'SS;. ^^ew, if any, aquatics. 
„ 6. Proteales. 
., 7. Santalales. 
,, 8. Aristolochiales. / 
,, 9. Polygonales. Bumex Hydrolapatlmm. Polygonum am- 
phihium. 
10. Centrospermse. Few, if any, aquatics. 
11. Ranales. NyinphcBacecB, Ceratop)hyUacecd,B,Animcu.\sicese, 
including Batrachium. 
,, 12. Rhgeadales. Cruciferae, including Suhularia and 
Jloripa. 
„ 13. Sarraceniales. No true aquatics. 
