408 SUMMAEY OF CURRENT RESEARCHES RELATING TO 



the ends of the separate rays whicli lie nearest the centre of the 

 equatorial plane. The separate rays behave differently according to 

 their position and surroundings. 



After the rays of the daughter-plane have bent at their polar 

 ends in the form of a hook, the fibres of hyaloplasm leave the pole, 

 and appear again on the equatorial side of the rudiments of the 

 daughter-nuclei as " connecting threads." While they are developing, 

 the young daughter-nuclei assume the form of a turban, which 

 favours the absorption of nutriment from the polar side by means of 

 the " polar rays." In consequence of this the transformation of the 

 ball of threads into tLe framework commences from the polar side. 

 The successive processes of formation of the mother-nucleus are 

 repeated in reversed succession after the longitudinal splitting of 

 the rays. 



Apical Cell of Phanerogams.* — P. Korschelt confirms the state- 

 ment of Dingier that the cone of growth in flowering plants is 

 developed from a single tetrahedral apical cell, by the separation of 

 daughter-cells. This general law is derived from the observation not 

 only of Gymnosperms (Pinus Abies, P. orientalis, P. canadensis, Taxo- 

 dium distichum, and Ejpliedra vulgaris), but also of Angiosperms (Elodea 

 canadensis, Lemna minor, Ceraiojphyllum suhmersum, and Myriojjhyllum 

 verticillatum). 



Nettle-fibre. f — J. Moeller has made a histological examination 

 of the fibres of the common stinging nettle, TJrtica dioica, with the 

 following results : — 



The primary bast-bundles of the stem do not form a connected 

 ring, and its fibres are mostly separated by intermediate parenchyma. 

 The cortical parenchyma is not sclerenchymatous. At the base of the 

 stem the fibres are mostly about 0-12 mm. in diameter; higher up 

 they are thinner ; but even at the summit they have a diameter of 

 • 04 mm. The thinnest fibres of the nettle are therefore as thick as 

 the thickest of hemp. In consequence of their isolation they are 

 seldom polygonal. At the commencement of the time of flowering, 

 the fibres in the upper portion of the stem only are completely 

 thickened ; those in the lower part have still large cavities. There 

 are no pore-canals. Fibres were measured 22 mm. in length ; they 

 are very irregular in form. They consist of nearly pure cellulose; 

 their behaviour with cuoxam is characteristic. They swell with 

 extraordinary rapidity from without inwards ; a sharply differentiated 

 internal layer resists the action for some minutes ; but this is also at 

 length dissolved ; and, in addition to a small quantity of the con- 

 tents of the fibres, a delicate network remains, the primary membranes 

 of the parenchyma-cells which surrounded the fibres. 



In the opinion of the writer, the want of secondary bast-bundles, 

 and the diflficulty of separating the fibres completely from the sur- 

 rounding parenchyma, present insuperable difficulties in the way of 



* Ber. Deutsch. Bot. Gesell., i. (1883) pp. 472-7 (1 pi.). 



t Deutsch. Allg. Pulytechn. Ztg., 1883. See Bot. Centralbl., xvii. (1884) 



