Correspondence. 332 [May 1907. 



THE ABSORPTION OP NITROGEN BY PLANTS. 

 Dear, Sir,— I enclose a cutting from an Aberdeen paper re " Absorption of 

 Nitrogen by Plants," which may interest some of your readers, in view of the recent 

 correspondence there was on the subject, in the local papers. Mr, Trail is the 

 Professor of Botany in Aberdeen University. 



Yours faithfully, 



J. M. URQUHART. 



(Ext? act from the Aberdeen Free Press.) 

 I recognise Mr. Jamieson's right to hold his own beliefs as to the mode of 

 absorption of nitrogen from the atmosphere, and I respect the sincerity with which 

 he works, and the courage that he shows in upholding what he believes to be true, 

 against what he considers to be of the prejudice that approaches persecution in the 

 refusal to do honour to a prophet in his own country. I have examined carefully 

 the evidence he has put forward in support of his views, and have formed my own 

 conclusions on it : but I have not felt called on to make a statement of these 

 conclusions, apart from the bearing on my work as a teacher. But the reticence 

 that was permissible from uuwillingness to appear to prejudice Mr. Jamieson's 

 investigations, and from feeling the uselessness of controversy on a subject in which 

 the evidence on each side can be of interest to only the few to whom study has made 

 it more or less familiar, can no longer be maintained when Mr. Jamieson claims me 

 as a convert to his views, even in part. I do not doubt his belief that I am so ; but 

 it is only an example of the very slight grounds on which he is able to arrive at a 

 conclusion favourable to his views. That belief rests on an absolute misunder- 

 standing alike of what I said and of the problem that he is seeking to solve. With 

 reference to his argument that a tree, after growing many years in a soil, left that 

 aoil not impoverished in nitrogen to a degree comparable with the nitrogen present 

 in the tree, and that the plant itself must have drawn the excess directly from the 

 atmosphere, I suggested that the argument was not conclusive. It did not take 

 account of what I believe is admitted by everyone acquainted with the work of 

 recent years on the microscopic organisms in the soil, namely, that by their action 

 compounds of nitrogen are being constantly added to the soil, and brought within 

 reach of the roots of green plants. It is generally held that plants do obtain 

 nitrogen from the air in this way ; but this is absolutely distinct from Mr. Jamieson's 

 claim that he has proved that green plants absorb it directly from the atmosphere, 

 and that the young hairs are the organs of absorption. On this point, I think, after 

 the most careful and unbiassed examination of the evidence that I could make, that 

 he has failed to prove his case, and that he has so completely misunderstood the 

 structures examined by him as to make impossible a true interpretation of their 

 functions. 



In what follows I shall look at and discuss his evidence only as a botanist; 

 accustomed to the use of the microscope and of the tests employed, and familiarised 

 by years of study with the structures of plants, and with the contents of the cells 

 from their earliest to their mature stages, and also with the conditions under which 

 plants grow, as learned by much time spent in studying them in their natural homes. 



Turning to the mode of absorption of nitrogen that Mr. Jamieson claims to 

 have discovered, it consists, so far as I can follow his descriptions and figures in the 

 absorption of the nitrogen at the tips of the young hairs in cells which contain 

 chlorophyll or the substance that gives the green colour to plants. This absorption, 

 he supposes, leads to the production of nitrogenous compounds, which are carried 

 down into the leaves at first in a fluid state by narrow tubes, or rather by a cylinder 

 around the space ; and afterwards the more solid material passes down the centre of 



