J. H. Gilbert— Points in connection with Vegetation. Ill 



nitrogen indicated. In most cases there was much less gain 

 thanlhis, or a slight loss. There was in fact nothing in these 

 results to lead to the conclusion that either the Gramineae, the 

 Leguminosae, or the buckwheat had assimilated free nitrogen. 



The lower part of the table shows the results obtained in 

 1857 and 1858, in the experiments in which the plants were 

 supplied with known quantities of combined nitrogen in the 

 form of a solution of ammonium sulphate applied to the soil. 

 The ii.un- or losses unue n little higher in these experiments, 

 in which larger quantities of nitrogen were involved, but they 

 are always represented by units of milligrams only, and the 

 losses are higher than the gains. Further, the gains, such as 

 they are, are all in the experiments with the Graminea?, while 

 there is in each case a loss with the Leguminosae, and with the 

 buckwheat. On this point it should be stated that the growth 

 was far more healthy with the Graminese than with the Legu- 

 minosae, which are even in the open fields very susceptible to 

 the vicissitudes of heat and moisture, and were found to be 

 extremely so when enclosed under glass shades. It might be 

 objected, therefore, that the negative result, with the Legumi- 

 nosae are not so conclusive as those with the Gramineae. How- 

 ever this may be, taking the results as they stand, there is 

 nothing whi tead to the conclusion that either 



the Gramineae or the Leguminosae can take up and . - 

 the free nitrogen of the atmosphere. We, indeed, do not hesi- 

 tate to conclude from our own experiments, as Boussingault 

 did from his, that the evidence is strongly against the supposi- 

 tion that plants can so avail themselves of the free nitrogen of 

 the atmosphere. 



Independently of the action suggested as possible by M. G. 

 Ville, that is between free nitrogen and nascent or ozonized 

 oxygen within the plant itself, it has been supposed that the 

 frpp nitrogen of the atmosphere may unite with the nascent 

 SB, or ozone, as the case may be, evolved by the plant, 

 yield nitric acid. In our papers above referred to we 

 nave given reasons for supposing that such actions are not 

 likelv to take place; but whether they do or do not, it is at 

 any rate certain that in our own experiments we have not been 

 able to persuade plants to avail themselves of this happy 

 faculty of producing their own nitrogenous food. With regard 

 to the action supposed possiblv to take place externally to the 

 plant itself, if it were ' 

 should expect some, at 

 gen to be collected i 

 phere; but we have seen how ir 



combined nitrogen in those deposits to account for the yi 

 nitrogen, even of the Gramineae, and still less can it sa 

 torily explain the yield in the Leguminosae and other plai 

 [To be continued.] 



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