128 Morphology BOOK i 



The treatise of Le Maout and Decaisne which appeared in 

 1868 became the textbook of the time. It gave a much 

 better presentation of the subject and was beautifully illus- 

 trated. Bentham however criticized it severely as teaching 

 that ' affinities are to be determined by a calculation of 

 resemblances estimated according to a fixed scale of the 

 relative value of characters '- 1 It took too little account 

 of the new current of thought with regard to evolution. 



A classification of the Phanerogams of a totally different 

 nature appeared in 1898 from the pen of the veteran 

 botanist Van Tieghem. He applied anatomical characters 

 as marks of relationship, and laid stress on many which had 

 not previously attracted attention in that connexion ; one 

 especially was the development of the growing point of 

 the root, and the morphology of its piliferous layer. On 

 this line he separated the Nymphaeaceae from the rest 

 of the Dicotyledons, and the grasses from the Monocotyle- 

 dons and united them into a third great group, co-ordinate 

 with Monocotyledons and Dicotyledons, calling them 

 Liorhizeae Dicotyleae. He held the grasses to be really 

 dicotyledonous, an assumption which was clearly open to 

 criticism. His divisions of Monocotyledons were based on 

 the character of the corolla and the position of the ovary. 

 Those of the Dicotyledons were founded on the presence or 

 absence of perfect seeds. Those with seeds were further 

 subdivided on the lines of the number of the integuments 

 of their ovules, and further again on the characters of the 

 corolla. 



This system met with little favour outside France. It 

 was criticized with some severity by Bayley Balfour, who 

 disputed the interpretation of the anatomical structure of 

 the embryo of the grasses, and denied the existence of any 

 metamorphosed second cotyledon. Balfour's views were 

 accepted generally in England. 



1 Belfast Address, 1874. 



