la 



INTRODUCTION. 



To this type belong the majority of the Dicotyledons. Helianthus annuus, Fago- 

 pyrum, Raphanus sativus, Myriophyllum, species of Salix, Casuarina stricta, Lmum 

 usitatissimum, and Primulaceae ' have been carefully investigated. 



4. The fourth Angiospermous type (Fig. 5) is observed in those of the 

 Cucurbitacese (Cucurbita) and Papilionaceae (Pisum, Phaseolus, €icer) which have 

 been investigated. Here a common initial zone extends transversely over the 

 pundum vegetationis ; by the divisions in this arise, on the side towards the 



FIG. 5.— (aio) Pisum satiwim. Median longitudinal section tlirough tlie apex of tlie root, after Janezewskt p—p plerdme, ' 

 ^—r periblein, y common transverse initial zone, t its lateral continuation, 



root-cap, successive layers, which are added to the conical middle portion of the 

 latter. On the side of it facing the body of the root arise a massive plerome-cylinderi j 

 ^nd a periblem many layers of cells thick, haviiig approximately the form of a hoUovf 

 cylinder open towards the initial layer. From its- margin the transverse initial zone 

 of meristem curves itself round, so to speak, over the adjoining outer surface of 

 the periblem, and acts here for a further space as initial layer, on the one hand 



' Kamienski, Zitr vergl. Anatomie d. Primeln,- Strassburg, 1875. 



