AGRICULTURE AND DENDROLOGY. 
15 
to apply the night-soil only after it has been well decom¬ 
posed, the reason given being that the plants manured with 
fresh dung, are liable to wilting. I have tried, with the 
cooperation of Mr. Y. Komi and others, to find an expla¬ 
nation for this difference between the action of fresh and well 
rotted excreta, and may give here a brief sketch of the 
results 1 ' obtained. 
Neither the fresh nor the decomposed excreta contain, 
so far as our knowledge goes, direct poisons to the plants, 
and also the acid reaction of the former cannot disturb the 
vegetation, because all ordinary soils possess to a high 
degree the power of neutralizing the acid phosphates to 
which the reaction of the urine is due, and besides this, 
plants even prefer acidifient nutritive fluids to alkaline ones. 
It furthermore seemed, a priori, most probable that the 
injurious action of the fresh excreta might be caused by a 
soluble ingredient, since the wilting appears as a matter of 
course only in young crops upon top-dressing them with 
the dung and since the roots cannot be reached in this case 
by the undissolved portions of the manure. Now the fresh 
excreta are distinguished from the decomposed particularly 
by their content in urea, a soluble compound of weak affini¬ 
ties which is not likely to enter chemical combinations in soils 
and thus to be retained in the superficial layers in the so 
called absorbed state, as is the ammonia of decomposed 
dung. However, as it was not yet known whether 
the urea is capable of undergoing absorption or not, we 
undertook some researches on this subject. Of the air dry 
surface soil of the paddy field of Komaba 50 grams digested 
for 48 hours, with 100 c. c. of solutions of urea containing 
in the said volume 4.835 resp. 2.418 grams of urea did not 
take up any amount of the latter substance, while, when 
1) A full record of these researches has already been published in 
“ Landwirtschaftliche Jahrbücher," vol. 15, 1880, p. 712. 
