Evolution of Monocotyledons. 293 
Alisnia reacts serologically to Magnolia , thus showing, according to 
Mez and Gohlke, direct relationship between the two forms. 1 
Maneval (47) has recently studied the development of Magnolia and 
Liriodendron, and concludes that the Magnoliacese or related forms 
represent the most primitive of existing Angiosperms. Porsch (54, 
p. 589) sees in the floral nectary a valuable phyletic character 
giving further support to the view that Monocotyledons have been 
derived from Dicotyledons through such forms as the Polycarpicae. 
Finally, in a study of the development of Butomus umbellatus, 
Holmgren (35) draws attention to the frequent formation of several* 
celled archesporia in this species, and notes similar formations in the 
Ranunculaceae. He does not insist too strongly upon the point, 
however, as many-celled archesporia are found in widely different 
plants. 
Although the majority of botanists have now been led to regard 
Dicotyledons as representing the primitive stock—or at least to 
take up a non-committal attitude—one or two writers still believe, 
on anatomical grounds, that Monocotyledons are the more primitive 
and themselves gave rise to Dicotyledons by the splitting of the 
one original and primitive cotyledon. One of the chief supporters 
of this theory is Lyon (44, 45, 46) whose work on Nelumbium con¬ 
vinced him that in this form the development of two cotyledons may 
be traced through the division of a single terminal member, 
homologous with the single seed-leaf of Monocotyledons, which are 
to be derived directly from a primitive monocotyledonous Angio- 
sperm stock. In order to account for the terminal position of this 
cotyledon, he suggests that it is not a phyllome, but an organ sui 
generis , comparable with the foot of Vascular Cryptogams, or with 
the sucker in Gnetwn or Welwitschia. Lyon’s theory of the 
primitiveness of Monocotyledons and their production of a dicotylar 
race need not be considered further, for it has not received any 
consistent explanation, nor are the anatomical (and other) differences 
between the two classes accounted for (cf. Sargant, 62, p. 175). 
It may be safely concluded that on the whole, opinion at present 
inclines strongly towards the view that Monocotyledons have been 
derived from a dicotyledonous stock —a view suggested by Strasburger 
(69, pp. 317, 318) as long ago as 1872. Miss Sargant (57-62) has 
been largely responsible for the advancement of the theory, 2 and the 
work of other botanists, along similar or different lines from those 
followed by Miss Sargant, has contributed to its support. 
1 Stuchlik (70) gives a long list of references on the subject of Botanical 
Serology. 
* Cf- Moss (51, p. 207). 
