JI4 BOTANICAL GAZETTE [October 



universally since his time. It is at variance with modern ideas of alternation 

 of generations and its significance. It fails to preserve the unity of the 



+ 



archegoniate series, but breaks it in two in the middle, separating closely 

 related forms and throwing Anthoceros into one subkingdom and Phyllo- 

 glossum into another. This is distinctly reactionary and opposed to the great 

 current of embryological research from Von Mohl to Bower. The further 

 subdivision by Van Tieghem of hisDiodees xnio Exoprothallees 2iTidEndopro- 



thalleh is equally artificial and objectionable. 



Turning now to a matter of detail. Van Tieghem places at the bottom 

 of his class Homodiode^s the Inovulees, characterized by the absence of 

 ovules. That brings the Loranthaceae practically to the bottom of the 

 dicotyledons, a most improbable position for a group of metaspermic par- 

 asites. Reduction in such plants might be expected in connection with 

 the high ecological specialization, but rudimentary structure would be 

 altogether astonishing in the family to which the mistletoe belongs. It is 

 rather in the aquatic medium that one would expect the primitive dicoty- 

 ledons, and, indeed, in such plants as Nelurabo, investigated by Lyon, and 

 Ceratophyllum, studied recently by Strasburger, the transition from the 

 monocotyledonous to the dicotyledonous habit can be seen. No system that 

 confuses reduced structures such as the placentation and ovule of the Loran- 

 thaceae with genuine rudimentary and simple structures can command wide 

 adherence. 



From top to bottom, both in the general and in the special portions, the 

 Van Tieghem classification seems to be an inversion of the truth. Neverthe- 

 less, it is a distinctly ingenious and stimulating piece of work, and has already 

 more than justified the labor spent upon it by its venerable and distinguished 

 author, in the light it has thrown upon some of the smaller and more obscure 

 groups of dicotyledonous plants. That it will be generally accepted is 

 improbable, and it seems doubtful whether it will gain much currency even 

 in France. The students of systematic botany, however, will be fully repaid 

 by reading it, for it is both brilliant and interesting.— CoNWAY MacMillan, 



Nearly fifty years ago there was described a species of Dischidia 

 with remarkable double pitchers. Pearson ^ now makes an examination of 

 the phenomenon. He finds double pitchers in four species of the genus: /?. 

 complex Griffith, Malacca; D, pectenoides Pearson, n. sp., Philippines; Dis- 

 chidia sp., Borneo; Dischidia sp., Borneo; the last two are undescribed, and 

 in very imperfect condition. The pitchers in these species, as in the other 

 pitcher-producing species of the genus, of which by no means all show this 

 characteristic, are morphologically leaves, the inner surface of the pitcher \ 



being homologous with the under surface of the foliage leaf. The origin of f 



9 Pearson, H. H. W, On some species of Dischidia with double pitchers. Jour. 

 Linn. Sec. 35: 375-390- pi- 9- 1902. 



I 



