ilaili/ periodical growth of Wheat and Barley. 157 

 These details may appear unnecessarily minute, but they 

 prove the scrupulous accuracy of the author, and shew what de- 

 cree of confidence his observations deserve. 



They are followed by a table, in which the author has con- 

 signed every two hours, from eight in the morning to ten at 

 night, the total height which each wheat and barley plant had 

 attained, from its base to its summit. The growth observed 

 during the hours of the night is also marked for each plant. 

 This table contains 383 observations marked in inches, lines and 

 fourths of lines. The author himself has extracted from this 

 table the principal data to form another, which we here copy, 

 and which presents the means of the periodical growth of each 

 plant for each of the six periods of the day, consisting of two 

 hours, and for the night period of twelve hours. 



Mean of the Periodical Growths of the Plants of Wheat and 

 Barley. 



These measurements are in fourths of lines, and their centesimal frac- 

 tions. 



Far from being surprised at the anomalies which this table 

 presents, in the periodical growth of the eleven plants compared 

 together, one is astonished at not finding these anomalies great- 

 er, when he recollects, 1st, That the plants were not of the 

 same species ; 2%, That they were in different stages of evolu- 

 tion at the period when the experiments commenced, and that 

 some of them had even 'ceased to grow before the end of the 

 experiment. 



The following arc the general results which the author de- 

 duces from his observations. 



