May 1A07J 



333 



Correspondence. 



the hair. He ascertained the presence of these nitrogenous compounds by the use 

 of iodine as a test, confirmed by other tests. There is no question as to existence of 

 nitrogenous substance in the young cells everywhere, since the living substance 

 (protoplasm) of a plant, like that of an animal, is present in every living cell and 

 suitable tests will show its presence ; but that does not warrant the assumption 

 that its presence proves the absorption of nitrogen from the atmosphere, and the 

 formation of nitrogenous compounds in those cells. Nor is chlorophyll found in the 

 young hairs, as Mr. Jamieson believes it to be. Such colouring matters as occur (as 

 his figures represent them in certain hairs) diffused in the fluid contents of cells are 

 quite distinct from chlorophyll ; which in all flowering plants is always confined to 

 certain sharply defined biscuit-shaped little pieces of protoplasm (chlorophyll-bodies 

 or chloroplasts), imbedded in the colourless protoplasm of the cells that form the 

 green tissues of leaves and other parts. 



Coming now to the supposed channels by which the more fluid compounds pass 

 down into the inner tissues, a careful study of Mr. Jauiieson's drawings and explan- 

 ations shows that the channels are neither more nor less than the cell walls, which 

 assume a yellow colour with iodine, but are not hollow. One hardly thinks of the 

 sides of a bucket as affording channels for the transference of the fluid it contains. 

 As for the passage of the more solid materials down the central space of a hair made 

 of a row of cells, the cell-walls that cross that space would seem to make the trans- 

 ference of solids somewhat difficult. I admit that I have found it difficult to under- 

 stand some of the figures, for they differ from anything that I have seen in the 

 examples of the same species examined by myself ; but one figure bearing the 

 explanation that it shows the channels that carry the fluid down from a hair to 

 distribute it among the cells below the epidermal layer, appears to me to represent 

 clearly by the channels the walls of palisade-cells, and by its so-called "cells" the 

 chlorophyll-bodies lying in characteristic fashion, not touching one another, but in 

 fact embedded among the colourless protoplasm within the palisade-cells. 



I have to apologise for occupying so much of your space, and for the technical 

 character of so much of the above, but it seems due to Mr. Jamieson to give reasons 

 (though by no means all) for not agreeing with his assertion that " the mode of 

 absorption was considered to have been demonstrated last year," or with the view 

 that to accspt the fixation of nitrogen by low organisms in the soil and on its surface 

 " constitutes acquiescence in the main point" that he claims to have proved. The 

 assumed mode of absorption, so far from being demonstrated, seems to me to rest 

 on errors both of observation and of interpretation so fundamental that they vitiate 

 his conclusions as to the functions of the parts in question. Iam not, therefore, 

 disposed to throw aside beliefs based on work of those whose methods 1 have been 

 able to test, and have not found wanting in favour of Mr. Jauiieson's views, however 

 much I may respect his sincerity, energy, and determination. I should have left 

 him to persevere without any such criticism of his views as this, had he not claimed 

 me as accepting them. I hold there is much to be explained in the laws of life and 

 nutrition of plants as well as of animals ; that only ignorance can presume to 

 dogmatise or to refuse to examine honest work on its own merits ; but that it is 

 incumbent on everyone who brings forward views opposed to those generally 

 accepted as the result of honest and competent investigation to test the new views 

 most carefully with full understanding of and experience in the best methods of 

 investigation. There is no desire so far as ever 1 have seen, to refuse new views a 

 fair hearing, but if they claim to prove the falsehood of those already held they 

 must themselves be fit to stand the severest tests of inquiry and criticism. To say 

 that Mr. Jamieson's appear not to stand these tests is not to commit oneself to the 

 assertion that the relation of the atmosphere to plant life is yet fully understood. 

 That relation is deserving of close and continued investigation.— I am, etc., 



James W. H. Trail, 



