334 SUMMARY OF CURRENT RESEARCHES RELATING TO 



number of vascular plants, including many Phanerogams, a Fern, and 

 one species of Equisetum. The author finds that by obstructing a part 

 or the whole number of the stomata by smearing the surface of the leaf 

 with vaseline or any similar substance, the normal respiratory intensity 

 is more or less diminished, the respiratory quotient is increased, the 



ratio = is increased, but there is no apparent effect upon the amount of 



anaerobic C0 2 set free. A similar experiment in connection with trans- 

 piration shows that obstruction of the stomata decreases transpiration. 

 The results tend to show that gaseous exchange takes place chiefly through 

 the cuticle, while water-vapour passes mainly through the stomata. A 

 few experiments have also been made in order to discover whether there 

 is any connection between the amount of chlorophyll present and the 

 respiration. It would appear that an abundance of chlorophyll augments 

 the respiratory intensity, and vice versa. The author regards the results 

 obtained as favourable to the " Zymasic Theory." 



Physiology. 

 Irritability. 



Influence of Gravity on Growth of Amanita.* — S. G. Streeter has 

 studied the influence of gravity on the direction of the growth of 

 Amanita phalloides and A. crmulata, with the object of determining 

 the reaction of common toadstools to the stimulus of gravity. As the 

 forms used were positively heliotropic, the experiments were performed ' 

 in a moist dark chamber. When young and strong specimens were 

 placed with the stipe in a horizontal position, the latter bent so as to 

 place the pileus in a horizontal position. Supra-curvature sometimes 

 occurred, but was neutralised unless the growth ceased too soon. The 

 responsive zone is in the tip of the stipe, and not in the pileus. Elonga- 

 tion takes place throughout the length of the stipe, but is ultimately 

 confined to the short zone just below the pileus. The duration of the 

 necessary stimulus is less than one minute. The latent period was from 

 40 to 60 minutes, but younger specimens responded more quickly than 

 older ones. 



Chemical Reagents in Relation to Wheat-seedlings.f — H. S. Reed 

 has investigated the transpiration in relation to the growth of wheat- 

 seedlings when under the influence of certain chemical reagents. 

 Phosphates of lime and sodium increase transpiration, while salts of 

 potassium decrease it. Inorganic acids retard transpiration, while 

 variable results were obtained with organic acids. Pyrogallol and tannic 

 acid increase transpiration. All the effects produced by the different 

 chemicals appear to be due to the activity of the ions, e.g. ions of 

 potassium always produce an inhibiting action, irrespective of the acid 

 ions present. Substances such as oxalic acid, pyrogallol, etc., which 

 occur naturally in plants appear to influence transpiration independently 

 of other factors. Further investigations on the lines of the present work 

 would probably result in practical advantages in agricultural operations. 



* Bot. Gaz., xlviii. (1909) pp. 414-26 (13 figs.), 

 t Op. cit., xlix. (1910) pp. 81-109 (9 figs.). 



