1756 AGRICULTURAL BOTANY, CHEMISTRY AND PHYSIOLOGY OF PLANTS 



took place by comparing the gas formed by two i)lants, one of which 

 was supplied with nitrogen in the shape of nitrate and the other with 

 ammonium salts. 



Radishes were grown in long necked flasks each of whi^h was connected 

 with a mercury manometer. The culture medium consisted (per flask) 

 of 60 cc of fine broken pumice and -|Occ of nutrient solution containing 

 nitrogen at the rate of 6.0 gm. of ammonium chloride or i gm. of potassium 

 nitrate per litre. Throughout the experiment aseptic conditions were main- 

 tained. As soon as the seeds had been sown the neck of each flask was sealed , 

 enclosing a volume of air which amounted to about 120 cc. Every' day 

 manometer readings were taken not only for the flasks containing plants 

 but also for a control flask, so that corrections for pressure and tempera- 

 ture could be made. 



'After 35 days a plant receiving ammonium chloride had produced 

 0.994 gms. of green weight or 0.153 gnis. of dry matter. The internal pres- 

 sure of the flask fell for the first 9 days and then rose till it attained 2. 11 

 cms. of mercury, which was equal to 2.77 cc of oxygen and brought the to- 

 tal amount of oxjgen up to 22.5 per cent of the atmosphere in the flask. 

 At the end of the experiment the respiration quotient was determined. A 

 value of 1.02 was obtained. 



Where the plant was supplied with nitrate, 0.264 gms. of dry matter 

 were produced in 35 days and the internal pressure rose to 8.6 cms. of mer- 

 cury. The oxygen in the flask was increased by 13.74CC, raising the per- 

 centage in the flask to 28.8. The respiration quotient was 1.07. 



The fact that the flask containing nitrate increased its pressure more 

 than the flask containing the ammonium salt led the writer to conclude 

 that oxygen had been set free from the nitrate. Assuming that the increase 

 in pressure for plants growing in the same medium is proportional to the 

 dry matter produced, the excess of oxygen in the nitrate flask was deter- 

 mined, and it was found that for e\'er3- atom of nitrogen fixed by the plant 

 two atoms of oxygen had been set free. 



1270 - The Assimilation of Iron by Plants. — CiiAopim-b M. II. (Sidorine m. j.), 

 MocKoecKiu Ce.ibCKO-xo3fincmeennbti( irHcmumymh : Ka&edpa VacinHOio 3e.H- 

 Aedn,.zifi. II3^ peayAbmamoeo eeietnai^ioHHhixo u jaSopamnyHbiXo pa6omo. 

 Fodo ig-ii. To.Uo X-u, nodh pedaht(,ieu npo(/Jeceop(i JX. H. IIpflHiiniHiiKOBa 

 (Moscow Agricultural Institut, Prof. Prianichnikov's Laboratory, Results of plant 

 cultures in 1914) Vol. X, pp. 241-257. Moscow, 1916. 



The assimilation of iron by plants was studied in a series of water 

 cultures and sand cultures carried out at the Agricultural Institute at ]\Io- 

 scow. A first experiment with water cultures was undertaken to determine 

 the influence of carbonates on iron assimilation; the following nutrient so- 

 lutions were used: 



a) Knop's normal culture solutions containing per litre : 



Calcium nitrate i gm. 



Potassium nitrate 0.25 " 



Potassium chloride 0.25 " 



Potassium sulphate 0.25 " 



Potassium phosphate 0.25 " 



Ferric phosphate 0.20 " 



