562 Anatomie. 



In the second part of the paper the structure of a number of 

 schizocotylous seedlings is described and compared in each case 

 with the normal type. The species studied were Cannabis sativa, 

 Phacelia tanacetifolia , Antirrhinum majus, Scrophiilaria nodosa, 

 Amaranthus speciosus, Clarkia pidchella, Papaver rhoeas, Lepidium 

 sativum, Cavmichaelia aiistralis and Helichrysmn bracteatum. The 

 literature of schizocotyly is then dealt with and the subject is dis- 

 cussed in its theoretical aspect with critical reference to the views 

 of Hill and de Fraine. 



The author concludes that dicotyly is a primitive character — 

 whether for monocotyledons, or for teratological syncotyls and 

 schizocotyls, for polycotylous Proteaceae and Loranthaceae, or for 

 Gymnospermae. Agnes Arber (Cambridge). 



Goc, M. J. ie, Observations on the Centripetal and 

 Centrifugal Xylems in the Petioles o f C>'cafi?s. (Ann. 

 Bot. XXVIII. p. 183—193. 1 pl. 1 textfig. 1914.) 



Many different interpretations have been suggested b}^ different 

 botanists to account for the peculiarities of the foliar bündle in the 

 Cycads, and Chodat has drawn attention to the need for a reconsi- 

 deration of the whole problem. The object of the present paper has 

 been to throw some fresh light on the subject by means of an exa- 

 mination of live genera of Cycads including seven species, Cycas 

 circinalis, C. revoluta, Stangeria paradoxa, Dioon edide, Ceratosatnia 

 ntexicana, Encephalartos horridiis and E. villosus. The author points 

 out that the mode of transition from the stem type of xj^^lem to the 

 petiolar arrangement of that tissue has hitherto been generali}'" 

 overlooked. He also gives some interesting Information upon wound- 

 structures, but concludes that such structures artificially induced 

 are without any direct bearing on the phylogenetic Interpretation 

 of the bündle. The final conclusions are as follows: 



At the very base of the petiole the structure ot the vascular 

 bundles of Cycads is entirely centrifugal, and assumes different 

 forms, concentric, collateral, or a combination of both. The centri- 

 fugal xylem at the base is, at least in its main bulk, a secondary 

 growth. The centripetal xylem is a primary structure laid down at 

 an early age but only gradually lignified. The centrifugal xylem 

 and centripetal xylem are probably distinct in origin, juxtaposed 

 in response to phj^siological demands but morphologically discon- 

 tinuous. During most of the course along the petiole the two xylems 

 remain distinct, therefore the bündle is more properly called pseudo- 

 mesarch or diploxylic, The two xylems overlap at their ends. The 

 remains of centripetal xylem scattered at the base might point to 

 a time when it ran further down, perhaps into the stem. 



Agnes Arber (Cambridge). 



Hemenway, A. F., Studies on the phloemoftheDicoty- 

 ledons. II. The evolution ofthe sieve tube. (Bot. Gaz. LV. 

 p. 236—243. pl. 11. Mar. 1913.) 



A study of 140 genera of Dicotyledons leads to the grouping 

 of sieve tubes in three classes: 1) with a long tapering end wall, 

 and the lateral and terminal sieve plates alike; 2) with end walls 

 less oblique, and the lateral sieve plates less well developed; 3) with 

 end walls nearly at right angles to the length of the tube, and a 



