438 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the author comes to the conclusion that the horizontal position is due- 

 neither to heliotropism nor to geotropism, but to unfavourable vital 

 conditions, especially to the contamination of the air by small quantities 

 of poisonous gases. 



(4) Chemical Changes (including- Respiration 

 and Fermentation). 



Formation of Asparagin and Proteids in Plants. * — According to 

 E. Schulze, asparagin is not produced only during germination, but 

 also at subsequent periods, as for instance, during the development of 

 the leaf-buds. It occurs also in the roots of plants, sometimes in con- 

 siderable quantities, accompanied by amido-acids and other soluble 

 crystallisable nitrogenous compounds. 



Experiments by the same author f on the cultivation of Lu-pinus 

 luteus show that in germination a considerable decomposition of proteids 

 takes place. Most of the products are subsequently converted into 

 asparagin, which accumulates to a large amount, owing to the small 

 quantity of glucose present being insufficient to enable the asparagin 

 to be completely transformed into proteids. An increase takes place 

 both in the asparagin and in the proteids. 



The same author + adduces further evidence that asparagin can be 

 produced from other products of the decomposition of proteids. But 

 in the absence of light a considerable production of proteids can take 

 place only when all the other conditions are exceptionally favourable, — 

 when proteids are present only in small amounts, and when amides and 

 reducing sugar are abundant. 



From experiments on Brassica Napus and Daucus Carota, M. Iwau- 

 off § concludes that the formation of proteids goes on in the dark in 

 plants. The process can, however, proceed energetically only when there 

 is present an abundance of amides and a considerable amount of readily 

 available carbohydrates, as in the case of the onion. A considerable 

 amount of proteids was found in the leaves of Brassica iVflpws, which 

 must have been newly formed, 'unless it had migrated from the roots 

 in the form of albumin or pepton. 



Influence of Nutrition by various organic substances on the 

 Respiration of Plants. || — A series of experiments carried on by . 

 "W. Palladine led to the following general conclusions. The energy of 

 respiration depends on the quality of the combustible substance. The 

 substances employed are thus arranged in the order of their com- 

 bustibility : — fructose, glucose, saccharose, maltose, raffinose, glycerin, 

 mannite. Cut etiolated leaves respire but feebly, but the energy of 

 respiration increases sensibly after treatment with saccharose. Cut ends 

 of branches, on the other hand, respire energetically, but the energy 

 decreases after treatment with saccharose. In the absence of carbo- 



* Landwirth. Jahrb., xxvii. pp. 503-1(3. See Journ. Chem. Soc, 1901, Abstr. ii. 

 p. 332. 



t Tom. cit., pp. 51G-20. See Journ. Chem. Soc, 1901, Abstr. ii. p. 333. 



J Landwirth. Vers.-Stat., )v. (1901) pp. 33-44. See Journ. Chem. Soc, 1901 r 

 Abstr. ii. p. 184. Cf. this Journal. 1900, p. 608. 



§ Tom. cit., pp. 78-94. See Journ. Chem. Soc, 1901. Abstr. ii. p. 1S4. 



| Itev. Geu. de Bot. (Bonnier), xi. (1901) pp. 18-32, 93-6, 127-36. 



