734 



latter be nonrisherT through the younger stages from the soil, they, like the unu 

 leguminous plants, ean fix free nitrogen without the aid of these organisms lat< i 

 With most leguraiuous plants, however, the symbiosis with these organisms euabb 

 a more extensive assimilation. 



(11) The hypothesis becomes more probable, that the action of this symbiosis lies 

 more in the plants themselves than in the bacteria ; that is, that the bacteria by ^ 

 their presence act as a stimulus to the plant, rendering its inherent ability for nitro- j 

 gen assimilation more active. 



Investigations on the adherence to the foliage of potato plants 

 of compounds of copper used for controlling plant diseases, A. 

 Gerard (Compt. rend.. Hi (i^V^^, pp. :>34-23'J). — Observing the injury 

 to tlie potato crop by rot (Phytojyhthora infestans) iu 1800, due to the 

 excessive rains washing- the fungicides from the foliage and thus allow- ! 

 ing the parasites to develop unchecked, the author was led to institute 

 a series of experiments to test the persistency with which the various 

 coi)p('r mixtures wliich have been proi)Osed for controlling plant dis- | 

 eases adliere to the loliage. '■ 



For this purpose potato plants growing in large pots in a plant house 

 were treated in ditfenMit cases with Bordeaux mixture (ordinary, with 

 one half quantity of lime, and with addition of alum), copper-soda 

 solution, copper-lime saccharate (copper sulphate 4.4 pounds, lime 

 4.4 poun<ls, molasses 4.4 pounds, water -Ct gallons), and verdigris 

 (bil)asic acetate of copper) solution. The spraye<l plants in ea<'h ciise 

 were divided into 3 lots, which were sprinkle*! with water by means 

 of an api)aratus specially devised for the purpose, as follows: (1) 

 For 22 minutes at a rate corresi)onding to a rainfall of 17 mm.; (2) 

 for 6 hours at a rate corresjjonding to a rainfall of 15 jiim.; and (.'3) for 

 24 hours at a rate corresponding to a rainfall of 10 mm. One half of 

 the plants of ea<h lot were afterwards gathered, dried, and subjected 

 to analysi.s to determine the proportion •>f copper a<lh('ring to them. 

 The results showed wide variations as regards the dilferent treatments. 

 The Bordeaux mixture ai)peared to be more readily washed ott" than any 

 of the other compounds, but lessening the i)roportion of lime or adding 

 alum }»roduced no sensible imi»rov«'ment. Copjier soda and verdigris 

 solution showed iK)wer8 of adherence almost double that of the Bordeaux 

 mixture, while the copi)er-lime saccharate was not washed off at all, 

 excei)t in the case of violent sprinkling. The author concludes that of 

 the last three solutions convenience alone must determine the choice. 



Contribution to the study of the development of cereals, A. 

 Hubert [AriK. Ai/r»n., i^ (is''.'), p;>. S3-i7). — An;ilysesol wluMt ;nid <tat 

 plants in different stages of development ma<le at the Grignon Station 

 by the author, Dcherain, and others during a number of years past, are 

 tabulated and discussed. During the period iuunediately after germi- 

 nation the whole of the vital activity of plants is devoted to the develojt- 

 ment of their root systems. This explains why the assimilation of 

 nitrogen and mineral matter is most active at that period, as shown by 



