Evolution of Monocotyledons. 
303 
V. Conclusion. 
From the foregoing review it will be seen that there is very 
great diversity of opinion concerning the cause and manner 
of development of the Monotyledons, while their immediate 
ancestry, though generally thought to be dicotyledonous, is still a 
matter for discussion. The speculations for which Arber and 
Parkin (2, 3) have been largely responsible, concerning their more 
remote ancestry, have little more than a theoretical value. 1 They 
are intensely interesting, and are within the bounds of possibility, 
but in the present state of our knowledge, they are somewhat daring. 
The gap between Gymnosperms and Angiosperms is still waiting to 
be filled by discoveries as important as those of Pteridosperms and 
Bennettitales. 
1 See Oliver (53); Scott (64, p. 658); Lignier (38); Coulter and Chamberlain 
( 12 , p. 280) 
Botany School, 
Cambridge. March, 1914. 
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