440 Transactions. — Botany. 



millions of germs in a thimbleful of sncli soil. These numbers 

 are, it must be admitted, sufficiently bewildering. And what 

 are these microscopic organisms doing? A few of them are 

 undoubtedly injurious parasites ; others are the fungi and bac- 

 teria that live as saprophytes on decaying vegetable and animal 

 remains, and are the active agents in the fermentations and 

 putrefactions which resolve organic substances into the forms 

 of carbon-dioxide, water, and ammonia. Others have the 

 power of oxidizing ammonia first to nitrous and then to nitric 

 acid, and are doubtless the chief agents in nitrification, while 

 still others undo the work of the last by degrading the highly 

 oxidized salts of nitrogen, deoxidizing nitrates to nitrites, and 

 the latter to ammonia and even free nitrogen. 



Besides these, evidence is accumulating that points to the 

 existence of forms which, provided there are plenty of carbo- 

 hydrates available, can actually fix free gaseous nitrogen in 

 their living machinery, and compel it to enter into the organic 

 synthesis. Winogradsky, who has isolated and studied organ- 

 ism.s of this kind at the Pasteur Institute Laboratory, sug- 

 gests that in its life processes nascent hydrogen is set free, 

 vphich combines with the free nitrogen of the air to build 

 up ammonia. 



These results are still so recent that I have not heard of 

 their verification by other observers, but should they be con- 

 firmed they show us that the very process of nitrogen fixation, 

 which occurs normally in the root-nodules of leguminous 

 plants, takes place in microscopic organisms that lie de- 

 tached in the soil, and indicate possibilities of nitrogen 

 storage in the soil that have hitherto not even been sus- 

 pected. Winogradsky's observations, too, lend additional pro- 

 bability to the hitherto doubtful view that it is the bacteroid 

 cells that constitute the actual seat of nitrogen fixation in 

 the root-nodules of the Leguminosae. However this may be, 

 it is obvious that the whole question of the supply of nitrogen 

 to vegetation is taking new turns. We feel that we are steer- 

 ing on the brink of new and fruitful discoveries that may 

 revolutionise the whole practice of agriculture, and even re- 

 store the prosperity of the agricultural interest in spite of the 

 world-wide decline in the values of nearly all cereal and other 

 products which the soil yields. Let us, in conclusion, note 

 that the advances in knowledge which I have endeavoured to 

 explain have been won by eminent investigators, hailing from 

 every one of the great civilised nations of Europe. Original 

 memoirs relating to the investigations I have been discussing 

 have appeared in nearly every European language, and only a 

 polyglot could fully follow the more important researches in 

 this one subject. In these days when the jealous nations are 

 snarling at each other's heels, it is no small consolation to 



