192 SUMMAKY OF CURRENT RESEARCHES RELATING TO 



growth on the two surfaces of the leaf, the author finds that the flowers 

 of tulip and species of crocus show opening movements above the 

 maximum temperature for growth, and closing movements at tempera- 

 tures below the growth-minimum ; also that the movements occur in 

 rarefied air (20 mm. barometric pressure) and in pure oxygen, hydrogen, 

 and carbonic acid gas, and even in watery solutions of different salts 

 which may even be injurious to the plant, provided that the concentration 

 is not sufficient to cause plasmolysis. The author concludes that altera- 

 tions of turgidity in the tissue of the perianth leaves are the cause of 

 the movements. 



Thigmotropic Root-Curvatures.* — F. C. Newcombe has repeated 

 Sachs' experiments on the curvature of roots caused apparently by 

 pressure, and finds that the result varies according to the material of 

 which the small rods applied to the root-tip is made. Pins made of oak 

 or of the wood of yellow pine caused a strong bending towards the side 

 in contact in roots of maize, lentil, bean, and others, but no result 

 followed when wood of the white pine or of the tulip-tree, or glass, was 

 used. The author concludes that it is not the pressure of the 'attached 

 object which causes the bending of the root, but probably substances 

 injurious to the root which are imparted by the attached object. That 

 is to say, the supposed thigmotropic curvatures are traumatic. 



Influence of Loading on the Formation of Wood and Bast Ele- 

 ments in Weeping Trees, f — W. Wiedersheim, experimenting with 

 normal individuals and weeping varieties of ash, beech, mountain ash, 

 hazel, and wych elm, finds a shortening of the wood-cells in the loaded 

 branches. No other effect was produced on the wood. In the hazel 

 alone, the bast-ring was more strongly developed, and there was also an 

 increase in the number of stereides. 



Chemical Changes. 



Sugar in Ripe Fruits.! — A. de Muynck has analysed varieties of 

 ripe pears during the winter months, and finds that levulose is always 

 greatly in excess of glucose. The former varies from 70 to 93 p.c. of 

 total sugar, the latter from 7 to 30 p.c. He suggests the possibility of 

 a fermentation process by which the glucose is attacked, in order to 

 explain this great difference between the percentages in the two cases. 



Formation of Asparagine in Metabolism.§ — U. Suzuki finds, as a 

 result of experiments with barley and beans, that there was an increase 

 of asparagine in the shoots only when oxygen was present, whereas de- 

 composition of proteid goes on in absence as well as in presence of 

 oxygen. 



Lime in Phanerogamic Parasites. || — K. Aso finds evidence to 

 support the view that the presence of chlorophyll influences the relative 



* Beih. z. Bot. Centralbl., xii. (1902) pp. 243-7. 



+ Pringsh. Jahrb., xxxviii. (1902) pp. 41-69. 



X La Cellule, xviii. fasc. 2, pp. 441-5. 



§ Bull. Coll. Agric. Tokyo Imp. Univ., iv. (1902) pp. 351-6. See alao Journ. 

 Chem. Soc, lxxxii. ii. (1902) p. 684. 



|| Bull. Coll. Agric. Tokyo Imp. Univ., torn, cit., pp. 287-9.^ See also Journ. 

 Chem. Soc, 1.0. 



