468 GNETAL-ES [CH. 



the Cycads to the Angiosperms 1 . It has, for example, been sug- 

 gested by Hallier 2 that they are reduced Dicotyledons comparable 

 with the Loranthaceae and Myxodendraceae ; while Lignier and 

 Tison 3 regard them as a group of Angiosperms nearest to the 

 Amentales. The question of relationship between the Gnetales 

 and the Angiosperms, especially the difficult problems connected 

 with the endosperm, was fully considered by Pearson 4 in a paper 

 on the reproductive organs of Gnetum Gnemon published in 1915, 

 and in a later contribution 5 , published after his death, the morpho- 

 logical problems are reviewed in the light of more recent work. 

 The same subject is dealt with by Prof. Thompson 6 in a recent 

 paper in which he calls attention to the form of the inflorescence, 

 the arrangement of the parts of the flowers, the presence of an ovary 

 with a style, the germination of the microspores at some distance 

 from the nucellus, as evidence of affinity to the Angiosperms, and 

 concludes that the ancestors of the Angiosperms were 'not far 

 removed from the genus Gnetum. ' On the other hand some botanists 

 prefer to regard the Gnetales as a blindly- ending branch of Gymno- 

 sperms with no direct relationship to the Flowering plants. Difficult 

 as it is to believe that plants so different, when the sum of characters 

 is considered, as the Gnetales and the Bennettitales are off-shoots of 

 a common stock, it would be rash to assume that such resemblances 

 as have been emphasised by Miss Sykes and other authors have no 

 phylogenetic value. 



At the time of his death (November, 1916) Professor Pearson 

 was engaged upon a volume on the Gnetales: in April, 1916, he 

 wrote, 'A large part of the book on the Gnetales is written, though 

 it will need some revision.. . .As to the Gnetalean-Angiosperm 

 alliance, there must be one, I think, but at present I cannot bring 

 myself to believe that it is direct 7 .' Had Pearson been able to 

 complete his work it is certain that a statement of his most recent 

 conclusions would have enabled botanists to obtain a clearer view 



1 Arber and Parkin (07); (08); references to other authors will be found in these 

 papers. See also Lignier and Tison (12); Lignier (03); Lignier and Tison (11). 



2 Hallier (05) p. 153. 



3 Lignier and Tison (11). 



* Pearson (15 2 ): additional references to literature are given at the end of this 

 paper. See also Caporn (16). 



5 Pearson (17). 6 Thompson, W. P. (16). 7 Seward (17) p. ix. 



