THE ASH OP PLAJSITS. 157 



Pierre attributes the larger per cent of ash in the 

 strong plants to the relatively greater quantity of leaves 

 developed on them. 



Similar results were obtained by Arendt in case of oats. 

 Wunder ( Versuchs-St., IV, p. 115) found that the leaves 

 of small turnip-plants yielded somewhat more ash per 

 cent than large plants. The former gave 19.7, the lat- 

 ter 16.8 per cent. 



8. The reader is prepared from several of the foregoing 

 statements to understand partially the cause of the vari- 

 ations in the proportion of ashin different specimens of 

 the same kind of plant. 



The fact that different parts of the plant are unlike in 

 their composition, the upper and outer portions being, in 

 general, the richer in ash-ingredients, may explain in 

 some degree why different observers have obtained differ- 

 ent analytical results. 



It is well known that very many circumstances influ- 

 ence the relative development of the organs of a plant. 

 In a dry season, plants remain stunted, are rougher on 

 the surface, having more and harsher hairs and prickles, 

 if these belong to them at all, and develop fruit earlier 

 than otherwise. In moist weather, and under the influ- 

 ence of rich manures, plants are more succulent, and the 

 stems and foliage, or vegetative parts, grow at the ex- 

 pense of the reproductive organs. Again, different vari- 

 eties of the same plant, which are often quite unlike in 

 their style of development, are of necessity classed to- 

 gether in our table, and under the same head are also 

 brought together plants gathered at different stages of 

 growth. 



In order that the wheat plant, for example, should 

 always have the same percentage of ash, it would be nec- 

 essary that it should always attain the same relative de- 

 velopment in each individual part. It must, then, 

 always grow under the same conditions of temperature, 



