ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 483 



amount of water conducted diminishes from day to day, partly owing to 

 a blocking of the vessels with a resinous substance formed through the 

 disorganization of the contents of the sieve-tubes. The withering of the 

 leaves is probably due less to lack of water than to the action of injurious 

 substances passed iuto them from the dead cells. The withering leaves 

 show all the symptoms of dying, i.e. rapid loss of water, discoloration of 

 chloroplasts, and contraction of the mesophyll. The use of steam for 

 killing the stem-cells is not so satisfactory as the use of wax at 110 ° C. ; 

 the latter causes less disorganization of the cells, less injury to the leaves, 

 and does not cause marked decrease in transpiration. Stems, portions of 

 which have been killed by prolonged treatment with picric acid, 95 p.c. 

 alcohol, or CnS0 4 , conduct water for a comparatively long period, and 

 allow new branches to develop. Picrid acid, chromic acid, and HgCl 2 

 may increase the amount of water evaporated by poisoned plants, HgCl 2 

 causing the greatest loss of water. 



Reduction by Roots.* — 0. Schreiner and M. X. Sullivan have experi- 

 mented with wheat-seedlings to determine whether roots have reducing 

 powers, and may thus promote the fertility of the soil. It is found that 

 when seedlings are grown in solutions of methylen-blue, etc., the colour 

 is lightened, likewise in starch-iodide solution the colour is slowly dis- 

 charged. Experiments with neutral, acid, and alkaline solutions of sulphur 

 failed to show any hydrogenating action, and tests for the reducing 

 SH group also failed to give results. Seedlings grown in very dilute 

 solutions of KN0 3 reduce'd the nitrate to nitrite. Sodium selenite and 

 sodium tellurite were also reduced, but reduction was retarded by the 

 presence of free acids or alkalis or of toxic organic matters. The 

 authors find that seedling-roots possess a power of reduction from the 

 time of germination until the sixth or eighth dav, when it is at its 

 maximum ; a gradual decrease is then perceptible. Whilst power of 

 oxidation is retarded by acid reaction, the latter promotes reduction. 

 The reduction-power is most marked in the parenchymatous cells, and is 

 probably due to metabolic activity producing either an oxyorganic acid, 

 or a complex, unsaturated compound, or an unsaturated fatty acid. 



Latex Diastases of Broussonetia.t— M. G-erber contributes a note 

 dealing with his work on the latex of Broussonetia papyri/era L. The 

 author finds that the latex possesses properties similar to those of the 

 pancreas of higher animals, since it contains three diastases capable of 

 dealing with the fats, carbohydrates, and albuminoids of reserve food- 

 materials, and rendering them fit for assimilation by young leaves and 

 inflorescences. The activity of these diastases diminishes in autumn 

 and more so in winter, but it never ceases entirely ; in this respect the 

 latex diastases differ from those of seeds which cease their activity while 

 the seeds are latent, but this difference is accounted for, since B. papy- 

 rifera continues to live throughout the winter. 



All the three diastases are not equally strong in all kinds of latex ; in 

 some cases the lipolytic diastase is most active, in others the amylolytic, 

 and in others the proteolytic, the predominant diastase being in ac- 

 cordance with the nature of the food-reserve. 



* Bot. Gaz., li. (1911) pp. 121-30. 



t Comptes Rendus, clii. (1911) pp. 1611-14. 



