THE WHEAT CJJLTURIST. 37 



excretions have any effect, it can only be caused by the 

 difference in the quality left in the soil by different spe- 

 cies. Some of the plants known to exhaust the soil in 

 the highest degree, such as flax and box, have few or 

 no suckers to their roots and leave scarce any exuda- 

 tions. Eye and many other grasses deposit very little 

 in comparison with crucifers and cichoraceae. Hemp, 

 on the other hand, which is a great exhauster, exudes 

 a great deal by the roots ; so do wheat and barley, but 

 the exhausting effects of these plants may be traced to 

 other causes. Thus, then, although from these experi- 

 ments the fact of absorption and excretion from the 

 surface of organs of temporary duration on the young 

 shoots of roots is clearly demonstrated, we do not pos- 

 sess any data sufficient to affirm that the matter ex- 

 creted produces any effect whatever on the capability 

 of the soil to supply nutriment to other plants grown 

 in it. 



" One of the experiments made by Gasparrini is very 

 instructive as to the noxious effects of vegetable manures 

 in those first stages of decomposition which are so fa- 

 vorable to the development of moulds. In the month of 

 January he sowed seeds of Triticum spelta, or as it is 

 more commonly called Spelts, in a number of small 

 garden-pots filled with well-washed Yesuvian sand. In 

 one pot he placed a piece of young dead wood of Ailan- 

 thus glandulosus, in another a piece of bread, in another 

 a portion of a green potato, in a fourth a portion of a 

 radish root, in a fifth some parings of kid's hoofs and 

 bits of nutshells, in the sixth nothing, for the sake ot 

 comparison. The pots were all waterei with common 

 drinking-water, exposed by day to diffused light, and in 

 clear days for a few hours to the direct light of the sun, 



