354 Morphologie etc. — Varietäten etc. 



to ihat of the foliage-leaf of the Grass. That part of the cotyledon 

 which corresponds to the sheath of the foliage-leaf is only present 

 at an early stage of development, and later becomes completely 

 obscured. The coleoptile is part of the cotyledon, viz. that which 

 is represented in the foliage leaf by the ligule; the author considers 

 that the ligular nature is suggested by the early developmental 

 stages of the embryo, the vascular anatomy and the abnormal for- 

 king. The epi blast is part of the cotyledon, corresponding to the 

 auricles of the base of the lamina of the foliage-leaf in certain 

 Grasses. The cotyledon of the Grass differs in no essential fea- 

 ture from that of other Monocotyledons. The mesocotyl is the 

 elongated primary node. The position of the cotyledon in all 

 Monocotyledons is terminal, and it is the natural continuation and 

 termination of the hypocotyl. The balance of development of the 

 cotyledonary lamina and sheath may vary in favour of the latter in 

 certain cases, and at certain stages of the ontogeny, as in Diosco- 

 reaceae and Commelinaceae. In certain instances, as on a seedling 

 of Agapanthus and on Cyrtanthus (both belonging to the Amarylli- 

 daceae), the sheath may develop, at one stage or another, into a 

 second cotyledon. This is not an ancestral, revisionary character, 

 but a novel and progressive one. Agnes Arber (Cambridge). 



Ridley, N. K., On Endemism and the Mutation Theory. 

 (Ann. Bot. XXX. p. 551—574. 1916.) 



This paper is a criticism of Dr. VVillis's Contributions on the 

 "age and area" law of plant distribution, especially those in Phil. 

 Trans. Roy. Soc. B. CCVI p. 307 and Ann. Bot. XXX. 1916. p. 1. 

 No allusion is made to Willis 's more recent paper, extending the 

 same conclusion to the New Zealand flora (Ann. Bot. XXX. p. 

 437). The author considers that, in the case of Ceylon, Willis 's 

 arguments are vitiated by the fact that the classes of rarity, into 

 which Trimen, in his "Flora of Ceylon", distributes the plants 

 of this area, were based upon a study of herbarium specimens 

 rather than upon work in the field. He also suggests that some of 

 the plants in the "Very Common" class are introduced weeds, not 

 true natives. With regard to endemism, he points out that a large 

 number of the endemic species of Ceylon belong to monot5rpic 

 genera whose nearest affinities are often Malaj'an; the connexion of 

 the Malay,region with Ceylon must have been severed long ago, 

 so these endemies, the writer argues, are old inhabitants of Cey- 

 lon, not recent developments. They are the remains of an old rain 

 forest flora, isolated in the wet zone of the island. The author con- 

 siders that endemic species in Ceylon and elsewhere are nearly 

 all the relics of an old flora rapidly disappearing. He does not dis- 

 cuss Willis 's remarkable arithmetical results. 



It is scarcely possible to give a satisfactory summary of so con- 

 troversial a paper as the present: those who are interested in 

 Dr. W ill i s's "age and area" law will no doubt read it in extenso. 



Agnes Arber (Cambridge). 



Salisbury, E. J., Variations in Anemone itemorosa. (Ann. Bot. 

 XXX. p. 525—528. 3 textfigs, 1916.) 



For several years past the author has been engaged in the 

 stud}^ of Hertfordshire woodlands, in which the Wood Anemone is 



