Allgemeines. — Anatomie. 131 



"!-i 



Die günstigste Stellung rücksichtlich der Beleuchtung ist 

 an verticalen Achsen mit zahlreichen spiralig stehenden Blättern 



3-V5 



die Stellung -, die ungünstigste ist in diesem Falle die 



distiche Stellung. An geneigten Sprossen ist es umgekehrt, da 



ist erstere Stellung die ungünstigste, letztere die vorteilhafteste. 



Nur muss die Blattanordnung, um die günstigste Beleuchtung im 



diffusen Licht zu ermöglichen, eine laterale sein, und das 



trifft dann auch in der Natur durchaus zu. 



Winkler (Tübingen). 



Harvey-Gibson, R. J., Contributions towards a Know- 

 ledge of the Anatom y of the genus Selaginella. 

 (Annais of Botany. Vol. XVI. No. LXIII. p. 449. 1902.) 

 In this, the fourth part of these contributions, the author 

 deais with the morphology and structure of the root alone. 

 The nature of the „rhizophore" is first of all discussed, and it 

 is decided that the evidence brought forward, either on morpho- 

 logical, anatomical or developemental grounds is insufficient to 

 give it a cauline value as distinet from the subterranean portion 

 of the root. The roots of a large number of species were in- 

 vestigated, and their structure was found to be very uniform 

 throughout. The xylem is monarch with the protoxylem on the 

 side directed away from the apex of the stem. The phloem is 

 interrupted in front of the protoxylem. In 6". Lobbil the pro- 

 toxylem is separated from the metaxylem by several layers of 

 parenchyma. In 6 1 . Kraiissiana, dellcatissima and Poulterl the 

 xylem is centroxylic in the aerial portion of the root, and the 

 phloem extends all around the stele. In 6\ Oregana and ru- 

 pestris the metaxylem consists chiefly of true vessels. The 

 branching of the root is dichotomous, and at each dichotomy 

 the protoxylems of the two branch roots face each other, having 

 revolved through an angle of 90 degrees. In 6". inaequifolia 

 and Lobbil the upper, usuaily abortive root often developes into 

 a leafy shoot. In S. Lobbii the vascular System of this shoot 

 is monostelic at its base although higher up it differentiates 

 into two separate steles. D. J. Gwynne-Vaughan. 



Vuillemin, P., Le bois i nte r m e d i ai re. (Comptes rendus 

 des seances de l'Academie des sciences de Paris. T. CXXXV. 

 p. 1367. 29 dec. 1902.) 



L'auteur, apres avoir decrit la formation de vaisseaux peri- 

 cycliques extraligneux dans la racine du Gentiana ciliata, pro- 

 pose „de reunir sous le nom de bois intermediaire une 

 serie indeterminee de formations libero-ligneuses (y compris le 

 metaxyleme) qui s'ecartent de la notion classique de bois pri- 

 maire et de bois secondaire, soit par leur origine, soit par leur 

 position, soit par leur ordre de succession". Ce bois sert de 

 transition entre les divers tissus des bois classiques. 



Lignier (Caen) 



q* 



