452 SUMMARY OF CURRENT RESEARCHES RELATING TO 



made with species of the same genus to investigate the relation of nutrition 

 to the general habit of the plant. Investigations with Odontites verna,. 

 undertaken to decide the question as to how far parasitism was replace- 

 able by saprophytism, showed that while a proportion of plants grown in 

 river sand (4 out of 7) came to flower, a much larger proportion (11 out 

 of 12) reached the same stage in humus cultures. The tendeucy to form 

 haustoria for humus-feeding was a very slight one. 



Germination of Potato Tubers.* — H. Vochting finds that the 

 manner of development of shoots on a tuber is closely related to tem- 

 perature. At a temperature which only slightly exceeded the lower 

 limit at which germination begins, only tuber-bearing shoots were 

 produced, while at the optimum temperature leaf-shoots were exclusively 

 developed ; in the former case the root-development was small, in the 

 latter copious. The amount of water in the soil is also closely related 

 to the mode of growth. If little or no water be added then almost no 

 roots and no leaf-shoots are formed, but only tubers. On the other hand, 

 with a plentiful supply of water, numerous roots and subsequently leaf- 

 shoots, but no tubers, appear. The amount of water in the atmosphere 

 is also of importance. If insufficient, the shoots, whether etiolated or 

 arising under the influence of light, creep on the damp soil ; they are 

 hydrotropic. An increase in the supply of moisture in the air also 

 favours the development of leaves on the shoots, with insufficient moisture 

 only scales are formed. Variations in the amount of oxygen in the atmo- 

 sphere, on the contrary, exert no such formative influence on the course 

 of germination. The place at which a bud will develop can be deter- 

 mined by incidence of light rays. Finally the author theorises on the 

 mode of action of the various factors. 



Cultivation of Beet-root.j — P. P. Deherain and C. Dupont report 

 on the experiments on beet-root cultivation at Grignon in the years 

 1900 and 1901. Suggestions are made as to the variety most suited 

 to the soil, and the best distances apart for planting the roots. The 

 results also show that a permeable soil attains a high state of fertility 

 when it is kept damp either by summer rains or by watering ; under 

 these conditions a high ferment activity is reached and a very consider- 

 able quantity of nitrogen is converted into nitrates capable of being 

 assimilated. 



Leucine and Tyrosine as Food-stuffs.:}:— E.Schulze concludes from 

 the fact that they disappear during growth, that both of these substances 

 are assimilated by seed-plants. Loew and Bokorny had previously shown 

 that algae can utilise leucine. 



/' Yield of Leguminous Plants. § — O. Pitsch has ascertained the 

 amounts of total crop and of nitrogen yielded by various leguminous 

 plants. Vetches and peas gave greater yields than blue lupins, but the 

 roots of the latter penetrato the soil to a greater depth and thus prepare 

 the subsoil for future crops. 



* Bot. Zeit., lx. 1 (1902) pp. 87-114 (2 pla.). 

 t Comptes Kendus, cxxxiv. (1902) pp. 953-8. 



X Landw. Versuchs-Stat, M. (1901) pp. 97-106. See Journ. Chem. Soc., lxxxii. 

 (1902) ii. p. 165. 



§ Ann. Agron., xxviii. (1902) pp. 59-61. See Journ. Chem. Soc, 1. c, p. 286. 



