566 SUMMARY OF CURRENT RESEARCHES RELATING TO 



cular bundles of the petiole and primary leaf-blades occurs in plants 

 grown with free supply of calcium in the dark, and in an atmosphere 

 free from carbonic acid gas. When transpiration is reduced fewer 

 crystals appear, and when allowed to grow in a crowded state on filter- 

 paper in covered Petri dishes, crystals do not form for a long while. 

 The crystals are attached to or imbedded in a matrix of some pectic 

 substance, and occur in the first row of parenchymatous cells next to 

 the fibres in the bundles of the leaf-blades and petioles. They are always 

 on the side next to the wall of the fibre and not in the middle of the 

 colls. Where few fibres are present, -or where they are poorly developed, 

 as in plants grown in the dark and under reduced transpiration, crystals 

 are correspondingly diminished in number. They also decrease in num- 

 ber when the petioles are subjected to gradually increasing tension. 



Cyanogenesis in Plants.* — W. Pi. Dunstan and T. A. Henry have 

 investigated the nature of the poison contained in young plants of the 

 guinea corn (Sorghum vulgare), an important food-grain of the tropics. 

 The authors find that the young plant, but not the seeds or old plants, 

 when crushed with water yields prussic acid (about ■ 2 p.c. of the dried 

 plant). The acid is not present in the free state but is due to the action 

 of a hydrolytic enzyme, apparently identical with the emulsin of bitter 

 almonds, on a cyanogenetic glucoside which has been named dhurrin 

 from dhurra, the Arabic name for the plant. A formula is given for the 

 glucoside which differs from the other two known cyanogenetic gluco- 

 sides, the amygdalin of bitter almonds and the lotusin found by the 

 authors in Lotus arabicus, in being derived from dextrose and not from 

 maltose. 



Composition of Orchid Tubers.f — K. Eammelberg finds invert sugar, 

 sucrose, amylose, and cellulose in young and old tubers of eleven different 

 orchids. The old tubers contained the most cellulose, but generally less 

 invert sugar, sucrose, and amylose than the young tubers. The predomi- 

 nating constituent is amylose. 



Composition of Bananas.:}: — E. Leuscher publishes analyses of the 

 green and ripe husks, the unripe and ripe fruit without the husk, the 

 preserved fruit and the banana meal. The meal contains 6*98 p.c. of 

 crude protein. 



Chemical Demonstration of Nectaries in Pollen Flowers and 

 Anemophilous Flowers.§ — K. Stager has employed the chemical method 

 suggested and used by Paul Knuth, namely, use of Fehling's solution, 

 to determine presence of sugar-containing tissue in various flowers. 

 The flower was laid intact in the reagent for about 24 hours, the 

 solution with the flower was then boiled, and the flower washed with 

 cold water. Presence of sugar is indicated by a reddish precipitate of 

 cuprous oxide. By these means the author has demonstrated the presence 

 of nectar or a sugar- containing tissue, in some so-called pollen flowers, 



* Proc. Roy. Soc, lxx. (1902) pp. 153-4. 



+ Bied. Ceutr., xxxi. (1902) pp. 256-7. See also Journ. Chem. Soc., lxxxii. 

 (1902) ii. p. 420. 



X Zeit. offuntl. Chem., viii. (1902) pp. 125-34. See also Journ. Chem. Soc., lxxxii. 

 (1902) ii. p. 421. 



§ Beih. Bot. Centralbl., xii. (1902) pp. 34-43. 



