Nov. 1897.] BOTANICAL SOCIETY OF EDINBUKGH 71 



mineral matters required to enable the leaves to make this 

 organic matter was abstracted from the soil by the roots. 

 It cannot be doulited, for a vast mass of experimental 

 evidence is at hand to prove it, that that describes what is 

 in the main the theory of the nutrition of phanerogamous 

 plants; but while that is so, we must not regard as altogether 

 absurd and out of the question the probability that the 

 roots of phanerogamous plants may in some way be able to 

 absorb organic matter. That the plants can do without the 

 absorption of organic matter is not a proof that they do do 

 without it. Our forefathers were well aware that in the 

 accumulation of organic matter at the roots of plants, lay the 

 success of husbandry. Since their time we have come to 

 know that by the addition to the soil of what are called 

 fertilisers, which are frequently mineral substances contain- 

 ing no organic matters, a great increase of crop can be 

 obtained ; but evidence is not wanting to show that during 

 recent times the mere application of fertilisers has been in 

 many cases overdone, to the detriment of the texture and 

 condition, and even to the fertility of the soil. The result 

 is that at the present time there is a renewed appreciation 

 among the best farmers of the great value of organic 

 matter as an ingredient of the soil on which its fertility 

 depends. 



If the observations of Professor Frank be correct, some- 

 thing will have been done to reconcile two views of plant 

 nutrition that have hitherto been sharply at variance : but 

 there are some difticulties to overcome before his theory 

 of the symbiotic relation of the fungus, which he calls a 

 Mycorhiza, and the forest trees can be accepted, in so far at 

 least as the fungus is able to be regarded as supplying the 

 roots of the tree with organic matter. An obvious objection 

 to this view is that conifers and cupuliferous trees are pro- 

 vided with leaves w^hereby they can make their own organic 

 matter ; but, on the other hand, it may be said that there is 

 no reason why trees should not obtain their organic matter 

 from two sources. The one important observation which he 

 adduces in support of that view is, that in the roots of trees 

 nourished by the mycorhiza no nitrates are found. That is 

 certainly a remarkable circumstance, which very distinctly 

 differentiates them from most other plants in whose roots 



