224 HOW CROPS GROW. 



ods employed by him, though the best in use at that day, 

 and handled by him with great skill, were not adapted to 

 furnish results trustworthy in all particulars. Fourteen 

 years later, Arendt* at Moeckern, and Bretschneiderf at 

 Saarau, in Germany, at the same time, but independently 

 of each other, resumed the subject, and to their labors 

 the subjoined figures and conclusions are due. 



Here follows a statement of the Periods at which the 

 plants were taken for analysis : 



[still closed. 

 i.t Ti-iH 1 JTine 18, Arendt Three lower leaves unfolded, two upper 



) " 19, Bretschneider Four to five leaves developed. 

 9/1 T>O -nA i June 30, (12 days), Arendt Shortly before full heading. 



"M " 29, (10 days), Bn-tsHincidrr Tin- plants were headed. 

 Q/I i> ,.i 1 1 July 10, (10 days), Arendt Immediately after bloom. 



)a j " 8, ( 9days), Bivisclm.-icl.-r Full l.loom. 

 4th Pprirwl 1 Jul y 21, (11 days), Arendt Beginning to ripen. 



"M " 28, (20 days), Bn-tsclmoider " 

 fith Ppriorll jul y 31 ' (10 days), Arendt Fully ripe. 



M ] Aug. 6, ( 9 days), Bretschneider Fully ripe. 



It will be seen that the periods, though differing some- 

 what as to time, correspond almost perfectly in regard to 

 the development of the plants. It must be mentioned 

 that Arendt carefully selected luxuriant plants of equal 

 size, so as to analyze a uniform material (see p. 171), 

 and took no account of the yield of a given surface of soil. 

 Bretschneider, on the other hand, examined the entire 

 produce of a square rod. The former procedure is best 

 adapted to study the composition of the well-nourished 

 individual plant; the latter gives a truer view of the crop. 



The unlike character of the material as just indicated 

 is but one of the various causes which might render the 

 two series of observations discrepant. Thus, differences 

 in soil, weather and seeding, would necessarily influence 

 the relative as well as the absolute development of the two 

 crops. The results are, notwithstanding, strikingly ac- 

 cofdant in many particulars. In all cases the roots were 

 not and could not be included in the investigation, as it 

 is impossible to free them from adhering soil. 



1 1,1* Jl'nrlistiiiiin ili'f llilf< I'll ll"i i-.i . /.</'//:/'</. IvV.t. 



\lPaehtthimtvorMttniui <i< / Ha/erpflarae, Jour.fiir PraM. Cfiem.,16, 



