178 Anatomie. 



from root to stetn structure of 47 species belonging to 11 genera of 

 the Cactaceae is described. As regards their external morphology the 

 seedlings may be classified into two groups: 1. Those with a long 

 hypocotyl and more or less leafy cotyledons, with but little sign of 

 a succulent habit, viz. Pereskia, Opuntia, and Nopalea. 2. Those 

 with an ovoid or globular hypocotyl and small, sometimes micro- 

 scopic cotyledons, the succulent habit being well marked, viz. 

 Phyllocactus, Cereus, Piliceveus, Rhipsalis, Echinocereus, Echinopsis, 

 Echinocactus, and Mamülaria. 



The transition which always begins to take place immediately 

 below the cotyledonary node differs essentially in the two groups. 

 Group 1. is of Miss Sargant's Anemarrhena type; one bündle from 

 each cotyledon enters the hypocotyl and there bifurcates, the four 

 phloem groups thus formed constitute the four phloem bundles of a 

 tetrarch root; each protoxylem branches in three directions, the 

 two lateral arms fuse with the corresponding lateral arms of the 

 other cotyledonary Strand and form the two intercotyledonary root 

 poles, while the median protoxylem arms of each bündle give rise 

 to the two root poles of the cotjdedonary plane. 



Group 2. effects its transition according to Van Tieghem's 

 Type 3; two "double" bundles, one derived from each cotyledon, 

 give rise to a diarch root, by rotation, and fusion of the opposing 

 phloem groups. There is such considerable Variation in detail in 

 both groups that it is impossible to define a genus in terms of its 

 seedling structure. 



More or less well developed cotyledonary buds are present in 

 many species and take the form of tubercles with spines, such as 

 are found on the mature plant. They often have a vascular supply, 

 which, in some cases, plays an essential part in the transition phe- 

 nomena. The anatomy of the seedlings indicates that the adaptations 

 shewn by adult plants in response to their environment, which have 

 been impressed on the form of the young seedlings, have had a 

 corresponding influence on their internal structure. 



The appearance of the Anemarrhena type in the Cactaceae is 

 considered to have some bearing upon the question of the origin 

 of the monocotyledonous condition, and evidence is brought for- 

 ward to shew that Miss Sargant's "fusion" hypothesis is seriously 

 weakened by its discovery. 



The chief objection which has been urged against A. W. Hill's 

 "first leaf" hypothesis is shewn to be no longer valid, for the great 

 variability in the method of formation of the "double" bündle indi- 

 cates that it possesses no definite morphological value. 



E. de Fraine (London). 



Sperlieh, A., Bau und Leistung der Blattgelenke von 

 Connarus. (Anz. k. Ak. Wiss. Wien. XI. p. 204—205. 1911.) 



1) Die Basalpolster und Fiederblattgelenke von Connarus haben 

 durch Zentralisierung der Leitelemente charakterisierten Bau. Ihre 

 Bewegungen erfolgen durch Wachstum. Besonders an der Oberseite 

 sind viele tiefe Querfalten vorhanden, deren Bedeutung darin zu 

 liegen scheint, dass infolge enger Stellen dem turgeszenten volu- 

 minösen Organ das Ausbiegen bei der Einwirkung äusserer Kräfte 

 (wie Wind, Regenfall) erleichtert und es innerhalb gewisser Gren- 

 zen dadurch vor dem Zerreissen bewahrt wird. Der Bast ist nicht 

 durch Collenchym vertreten sondern zeigt eine eigenartige Modifi- 



