220 SUMMARY. OF CURRENT RESEARCHES RELATING TO 



(2) Nutrition and Growth, (including Germination, 

 and Movements of Fluids). 



Migration of Food-materials in the Leaves.*— Mr. G. M. Tucker 



and Mr. B. Tollens find that (in the plane-tree), the weight and the amount 

 of ash in the leaves increase until the death of the leaves, and then 

 slightly decline. The same is the case with silica and lime, but the 

 chlorine aud sulphuric acid show a continuous increase ; leaves gathered 

 in November contained three times as much sulphuric acid as leaves 

 gathered in June. Phosphoric acid and potassa increase very slightly 

 until the death of the leaves, after which they diminish to less than one 

 half their original quantity. The amount of nitrogen decreases continu- 

 ally to less than one-fourth of its original quantity. There appears to 

 be but very little retrogression of the food-materials from the leaves to 

 the stem or branches. Eain has very little, if any, washing out action 

 on the food-materials in the leaves. 



Chlorophyll- Assimilation in Solar Light which has passed through 

 Leaves-t — M. E. Griffon lias carried out a series of observations for the 

 purpose of determining the extent to which the power of assimilation in 

 leaves is affected by the light having passed through other leaves. Asa 

 rule, with the leaves of different trees, passing through a single leaf 

 does not greatly affect the power of light to decompose carbon dioxide ; 

 while, if the light have passed through two leaves, this power is so 

 weakened that respiration is more energetic than assimilation. The re- 

 duction in the assimilating power by passing through a single leaf varied 

 between as 1 : 7 in the case of the beech to 1 : 20 in the case of the ivy. 



Assimilation and Transpiration in Japanese Plants. J — M. K. 

 Shibata has investigated the phenomena attending metastasis in Japanese 

 species of bamboo. Starch is the chief reserve-food-raaterial in the 

 haulm, rhizome, and root ; its soluble product is cane-sugar. Tyrosin 

 and asparagin were both found, but tannin only very rarely. Phos- 

 phorus, potassium, chlorine, and magnesium are stored up in the reserve- 

 receptacles, the last especially in the sieve-tubes ; calcium and sulphur 

 were not usually to be detected directly. 



M. S. Kusano gives statistics of the transpiration of evergreen trees 

 in the winter in Japan. It attains its minimum at the end of January. 



From an observation of over eighty evergreen trees aud shrubs, Prof. 

 K. Miyake derives the following results. The amount of starch in the 

 evergreen leaves begins to decrease about the end of November, attain- 

 ing its minimum about the end of January, and beginning again to 

 increase by the end of February. As a rule Monocotyledons contain 

 less starch than Dicotyledons, Gymnosperms, or Pteridophytes, and 

 occasionally none at all. Starch is always present, even in the coldest 

 period of the year, in the mesophyll and in the guard-cells. The 

 stomates remain open in winter. 



Influence of Nitrogen on the Growth of Eoots.§— A series of ex- 

 periments carried out by Herr H. Miiller-Thurgau on the effect on the 



* Ber. Deutscli. Chem. Gesell., xxxii. (1899) pp. 2575-83. See Journ. Chem. 

 Soc , 1900, Abstr., ii. p. 35. t Comptes Rendus, exxix. (1899) pp. 1276-8. 



I Arb. Bot. Inst. k. Univ. Tokiu. See Bot. Centralbl., lxxx. (1899) pp. 169-72. 



§ VI. J.B. DeutsHi.-schweiz. Versuchsst. Wadensweil. See Bot. Centralbl., lxxx. 

 (1899) p. 74. 



