4()6 Anatomie. 



Les especes etudiees sont : Veronica hederaefolia L., V. 

 chamaedrys L., V. arvensis L., Stellaria media Vill., Cerastium 

 glomeratum Thuill. (= C. viscosum L.), Arenaria trinervia L. 

 et Scleranthus annuus L. Chez ces especes la position des 

 lignes piliferes longitudinales internodales est en rapport avec 

 la ramiiication. Chaque fois qu'ä l'aisselle d'une feuille se 

 developpe un rameau, l'entre-noeud de la tige imme'diatement 

 superpose ä ce rameau porte exactement au-dessus de celui-ci 

 tine ligne pilifere ä laquelle est exactement opposee une autre 

 ligne portee sur le premier entre-noeud du rameau axillaire. 

 Ce fait se produit meine lorsque la ramification est spiralee, la 

 disposition phyllotaxique etant opposee. Toutefois chez VA. 

 trinervia et le Sei. annuus des lignes piliferes un peu differentes 

 peuvent exister au-dessus des feuilles non axillantes. 



Lignier (Caen). 



Farmer, J. Bretland and Hill, T. G., On the Arrangement 

 and Structure of the Vascular Strands in Angiop- 

 teris eveeta and some other Marattiaceae. (Annais of 

 Botany. Vol. XVI. June, 1902. No. LXII. p. 371.) 



After a review of the existing memoirs of the anatomy of 

 the Marattiaceae, the authors describe the vascular arrangement 

 in the young plant of Angiopteris eveeta and Marattia fraxinea. 

 In the lowest part of the stem there is a Single central Strand 

 of vascular tissue, or siphonostele; above this it becomes 

 hollow enclosing a core of parenehyma; then it assumes a 

 polystelic condition, and finally commissural vascular Strands 

 (probably secondary in origin) are differentiated across the 

 intervening parenehyma connecting the opposite ends of the 

 cylinder. The commissural Strands gradually become more 

 complicated and the leaf-traces, which are at first Single Strands, 

 eventually consist of an elaborate network of anastomoses 

 which give rise to the series of zones described by M ettenius. 

 In the mature stem of Kaulfussia a peripheral vascular 

 network corresponds with the siphonostelic cylinder mentioned 

 above, while the commissural Strands are represented by a Single 

 axile Strand which is connected at intervals with the external 

 cylinder. In all three genera roots may arise from the central 

 as well as from the peripheral steles. 



The authors were able to demonstrate the oecurrence of an 

 external endodermis in the stems of Angiopteris, Marattia and 

 Kaulfussia, and in the two former they state that a certain 

 amount of secondary thickening takes place by means of a 

 cambium situated between the phloem and the xylem. 



The authors conclude with a discussion of the prevailing 

 views held as to the morphology of the vascular tissues. They 

 would prefer to dissociate the idea of the stele altogether from 

 the endodermis, and to emphasize the unity of the vascular 

 tissue as a whole as opposed to the circumjacent ground- 

 parenehyma whether central or peripheral. They regard the in- 



