220 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Structure of Podostemonacese.* — Prof. E. Warming has carefully 

 studied the anatomy and morphology of this order of flowering plants : 

 especially in the cases of Podostevion Ceratophyllmn and Mniopsis 

 Weddelliana and Glazioviana. The following are his chief points : — 



Stomata are altogether wanting. The epidermal cells are more or 

 less polygonal ; the cuticle is weak. The fundamental tissue consists 

 mainly of parenchymatous cells, usually somewhat elongated longi- 

 tudinally, especially the nearer they are to the fibrovascular bundles. 

 Their walls are often somewhat collenchymatous, swelling easily in 

 caustic alkali, by which a central lamella is distinctly visible. Inter- 

 cellular spaces are either entirely wanting or extremely inconsiderable. 

 All the cell-walls consist of pure cellulose, with the exception of the 

 tracheides of the xylem which are slightly lignified. Large quantities 

 of starch are often present in the fundamental tissue. The cell-walls 

 have a strong tendency to excrete silica, which frequently entirely 

 fills up the cell-cavities. This takes place in all the organs, but 

 especially in the ei^idermis. 



The roots are plagiotropous and distinctly dorsiventral, and are 

 hence often flat ; they contain sieve-tubes, and nearly always have 

 a root-cap, which is often oblique. They have a great power of 

 regeneration when detached. They attach themselves by means of 

 root-hairs, and of peculiar organs which he terms haptera, consisting 

 of protuberances which spring from the under side of the roots. 



Each fibrovascular bundle may be traced up into a leaf ; every leaf 

 receiving one bundle. They consist, in the stem, of soft bast (sieve- 

 tubes and cambiform) with a few spiral and annular vessels, and 

 are supported by a collenchyma which is especially developed on the 

 dorsal side ; its cells have a strong resemblance to true bast-cells. 

 The epidermis of the leaves is not strongly developed ; it contains 

 chlorophyll, and some of its cells are prolonged into short hairs. The 

 mesoijhyll resembles the fundamental tissue of the stem ; there is no 

 palisade-tissue. The vascular bundles of the veins are but feebly 

 developed ; sieve-tubes were not observed ; but, on the other hand, 

 sheaths, composed of true bast-fibres. 



Pitchers of Cephalotus follicularis.| — In continuation of his 

 previous researches on the morphology of the pitchers of pitcher- 

 bearing plants, A. W. Eichler traces the development of those of 

 Ceplialotus follicular is and Nepenthes pkyUampJiora. In the former plant 

 the pitcher is certainly the modified lamina ; in the latter possibly, 

 as Hooker believes, an appendicular formation ; in a certain sense an 

 excessively developed gland, separated by means of a stalk from the 

 flat basal part which represents the true lamina. Certainly the lid 

 of the pitcher of Nepenthes is not the true blade, as many suppose. 



Action of Light on Veg-etation.J — Professor N. Pringsheim thus 

 sums up the results derived from his previously recorded observations. 



* Videusk. Selsk. Skr. Eakke, VI. ii. (1881) 6 pi. (French abstract). See 

 Bot. Centralbl., viii. (1881) p. 108. 



t .IB. K. Bot. Gart. Berlin, i. (1881) pp. 193-7. 

 X MB. K. Akad. Wiss. Berlin, 1881, pp. 504-35, 



