EXTRACTS AND ABSTRACTS. 379 



Ueler den Vegetationspunkt der Dihotylen- Wurzeln. Von Jacob 

 Eriksson. (" Botanische Zeitung," October 13th, 1876.) — The views 

 of this author diverge from those of Holle above noticed, and are 

 nearer those of Janczewski. He admits four types of structure of the 

 dicotyledonous root, viz. : — 



1. The root-end has three separate Meristem -tissues, of which the 

 Plerom gives origin to pericambium, fibro-vascular bundles, and pith ; 

 the Periblem acts as the Meristem of the primary bark-layers, and 

 the Dermatogen or Dermatokalyptrogen produces the epidermis and 

 root- tip (Haube). The Periblem of this type arises cither from a 

 single cell-row (Initialenreihe), or from two or from three or more 

 cell-rows. 



2. Two Meristem-tissues are present in the root-end ; a Plerom 

 and a single tissue for the production of primary bark -layers, epider- 

 mis, and root-tip. 



3. Only a single Meristem- tissue is found. 



4. This shows Plerom and Periblem, but the latter is external, 

 and builds up the root-tip fi'om without inwards. 



Numerous instances of the occurrence of each type are given, and 

 a fuller treatment is promised at some future time. 



Aroideous Morphology. 



Zur Morpliologie der AracecB. Yon Dr. A. Engler. (" Botanische 

 Zeitung," February, 1876.) — The following are the chief results arrived 

 at : — 



MetJiod of Branching. — Pothos, Pothoideum, HeUropsis, and some 

 species of Philodendron branch monopodially, while in all other cases 

 a sympode is formed. 



Phyllotaxy . — In a few genera the leaves are distichous, but as a 

 general rule they are pentastichous. In Pistia almost a i arrange- 

 ment is found, and on the vegetating shoots of a few species of 

 Anthurium the leaves are pentastichous, while they are distichous on 

 the flowering shoots. 



Nature and Position of Leaves, ^c. — The inferior leaves (Meder- 

 blatter) of the side-shoots usually diverge in the h sense from the leaf 

 in whose axil the shoot is borne. Sometimes, with distichous examples, 

 the second of the inferior leaves of a shoot diverges from the first to 

 a greater extent than i, whilst the ^ divergence of the third leaf is 

 discontinued ; the fraction f almost represents this state of things in 

 Anthurium, and a still higher formula is required for Calla and 

 Rhaphidophora decursiva. The spathe — absent only from the highest 

 flowering-bearing branches of Pothoidium — is always placed in 

 accordance with the phyllotaxical system which prevails on the branch 

 bearing it. When side-shoots are developed from a flowering-branch, 

 they also produce flowers, and show, besides their basal leaf (Grund- 

 blatt), only the same kind of leaves as the shoot whence they are 

 derived produces above the leaf from whose axil the branching takes 

 place ; so that when the flowering-shoot stands in the axil of a foliage 

 leaf, the young branch borne by it developes, besides its basal leaf, 

 foliage leaves and a spathe ; but if the former arises from the axil of 

 an inferior leaf, the latter shows onlyjiinferior leaves and a spathe. As a 



