180 SUMMARY OF CURRENT RESEARCHES RELATING TO 



elusion that the changes in form of the alga are due to alterations in 

 the density of the nutrient fluid, i.e. in the osmotic pressure, rather than 

 to changes in its chemical composition. A high osmotic pressure de- 

 creases the vegetative activity of the alga, inhibits the production of 

 zoospores, and causes cylindrical cells to become spherical ; while a low 

 pressure increases the vegetative activity, accelerates the production of 

 zoospores, and causes cells in process of formation to become cylindrical. 

 The nutrient fluid used was Knop's solution. 



(4) Chemical Changes (including' Respiration 

 and Fermentation). 



Chemical Transformations during the Development of the Bud. * 

 — G. Andre traces a close analogy between the chemical changes which 

 take place during the germination of the seed and the development of 

 the bud. In the case chiefly examined — the development of the bud 

 of the horse-chestnut from the end of February till the first appearance 

 of the flower-buds — a large increase is observable in the amount of 

 soluble amide-nitrogen ; and the insoluble albuminoids are probably 

 formed at its expense. There is a remarkable diminution in the amount 

 of carbohydrates, which have been consumed by respiration. Other 

 changes correspond closely to those which take place in germinating 

 seeds. 



Photosynthesis.! — According to Dr. G. Pollacci, green organs of 

 plants which grow in sunlight give the aldehyde reaction with Schiff 's re- 

 agent ; while fungi do not, nor do leaves after having been kept for 

 some hours in darkness, or in an atmosphere containing no carbon 

 dioxide. Formic aldehyd reactions may also be obtained from expressed 

 sap. He concludes that formic aldehyd is produced by green organs 

 under the normal conditions of photosynthesis. 



Formation of Albuminoid Substances in the Dark.J — As the result 

 of a series of experiments on Zea Mais and Vicia Faba, Mile. M. Maliniak 

 comes to the following conclusions : — The higher plants can elaborate 

 albuminoid substances in the dark. These substances are probably 

 regenerated from amides in the presence of carbohydrates, of saccharose 

 as well as glucose. The specific nature of these carbohydrates is not 

 without influence on the amount of albuminoid substances regenerated. 



Formation of the Cinchona Alkaloids.§ — Dr. J. P. Lotsy has carried 

 on a series of observations for the purpose of determining the seat 

 of formation of the alkaloids in Cinchona succirubra and Ledgeriana. 

 He states that the sieve-tubes and the food-storing tissue of the seeds 

 contain no alkaloids, and that they appear in the cotyledons only after 

 these become green. The meristematic tissue is also free so long as it 

 is in an active condition. On the other hand, the alkaloids are always 

 found, at least at certain times, in the parenchyme-cells of the cortex, 

 wood, and leaves. On the death of these cells they may be absorbed 



* Cornptes Rendus, exxxi. (1900) pp. 1222-5. Cf. this Journal, 1900, p. 488. 

 t Atti 1st. Bot. Pavia, vii. (1899) pp. 1-21. See Bot. Gazette, xxx. (1900) p. 358. 

 ■Cf. this Journal, 1900, p. 343. 



J Rev. (ie'n. <le Bot. (Bonnier), xii. (1900) pp. 337-43. 



§ Bull. Inst. Bot. Buitenzorg, 1900. See Bot. Centralbl., lxxxv. (1901) p. 248. 



