760 SUMMARY OF CURRENT RESEARCUES RELATING TO 



Contents of the Cells of the Aril of the Nutmeg^.* — Hcrr A. 

 Tschircli finds the cells of tlie aril of Mijrixtica fragrnns to bo character- 

 ized by tlio presence of a large araonut of aniylodcxtrin. The grains 

 are from 2 to 10 /u, in size, and are coloured reddish-brown by an aqueous 

 solution of iodine; they do not contain even a nucleus of true starch. 

 They are usually rod-shaped, rarely roundish or disc-shaped, but often 

 curved or coiled ; they seldom exhibit distinct stratification. 



Phosphorus and Phosphoric Acid in Plants.f — MM. Borthelot and 

 G. Andre give tho results of some experiments with Amaraiithns 

 caudatus and A. pyramidalls, protected from rain but freely exjjosed to 

 the air, which show that tho plant absorbs both phosphorus and 

 potassium from the soil in the early stages of its growth, though tlie 

 amount of both, and especially of pliosphorus, inci'eases less I'apidly 

 than the weight of the plant. When flowering begins, the absorj^tion of 

 phosphorus practically ceases, but the absorption of potassium continues 

 so long as the plant grows, and the increase in the quantity of this 

 element during flowering is very considerable. The increase in the 

 quantity of nitrogen is almost proportional to the increase in tho weight 

 of the plant up to the beginning of inflorescence, although somewhat 

 smaller in the early stages of growth. When tho i)lant flowers, the 

 total quantity of nitrogen increases but little, and therefore the propor- 

 tion of this element decreases. In a soil containing about 8 grams of 

 potassium acetate per kilo., the plant grew with some difficulty, but 

 those w^hich survived became much larger. They contained nearly 

 twice as much potassium as under normal conditions, but tho increase 

 in the amount of phosjihorus followed the ordinary law. 



From the results detailed in this paper, it follows that manures con- 

 taining phosphorus and nitrogen are of no value after the jilant has 

 begun to flower, but manures containing potassium may be useful 

 throughout the whole period of growth. 



(3) Structtire of Tissues. 



Oil-receptacles in the Roots of Compositse.l — Herr R. Triebcl gives 

 the following general results from the examination of a number of 

 species. 



The oil-passages are always the result of the tangential division of 

 the protecting-sheath (endoderm). In most cases they always remain in 

 contact with the protecting-sheath ; exceptions occur in Ligularia and 

 Telckia. The cells surrounding the oil-passage contain more i^rotojilasm 

 than the other cells, in jn-oportion to the size of the passage ; as tho oil- 

 passage increases in size, these cells become shorter by horizontal 

 division. Fully formed oil is never found outside the oil-passage ; the 

 protoplasm of the passage-cells ajipears to take an important part in its 

 formation. Although formed in the protecting-sheath, the walls of the 

 oil-passage are never suberized ; even in comparatively large passages 

 the walls are thinner than those of the surrounding cells. When mature 

 the oil is often entirely replaced by protoplasm. They are intercellular 

 spaces with no special wall of their own ; they never contain starch. No 



* Ber. Deut8ch. Bot. Gesell., vi. (1888) pp. 138-41. 

 t Comptes Rendus, cvi. (1888) pp. 711-6. 



* Nova Acta Acad. Caes. Leop.-Carol. Germ , i. (1887) pp. 1-44 (7 i>l.s.). Cf. this 

 Journal, ante, p. 447. 



