Chap. I. 



INTRODUCTORY REMARKS. 



17 



"The observations as I received them are shown in columns II. 

 and III., where they certainly have no prima facie appearance of 

 regularity. But as soon as we arrange them in the order of 

 their magnitudes, as in columns IV. and V., the case is materially 

 altered. We now see, with few exceptions, that the largest 

 plant on the crossed side in each pot exceeds the largest plant 

 on the self-fertilised side, that the second exceeds the second, 

 the third the third, and so on. Out of the fifteen cases in the 

 table, there are only two exceptions to this rule. We may 

 therefore confidently affirm that a crossed series will always 

 be found to exceed a self-fertilised series, within the range of 

 the conditions under which the present experiment has been 

 made.' 



" Next as regards the numerical estimate of this excess. The 

 mean values of the several groups are so discordant, as is shown 

 in the table just given, that a fairly precise numerical estimate 

 seems impossible. But the consideration arises, whether the 

 difference between pot and pot may not be of much the samo 

 order of importance as that of the other conditions upon which 

 the growth of the plants has been modified. If so, and only 

 on that condition, it would follow that when all the measure- 

 ments, either of the crossed or the self-fertilised plants, were 

 combined into a single series, that series would be statistically 

 regular. The experiment is tried in columns VII. and VIII., 

 where the regularity is abundantly clear, and justifies us in 

 considering its mean as perfectly reliable. I have protracted 

 these measurements, and revised them in the usual way, by 

 drawing a curve through them with a free hand, but the re- 

 vision barely modifies the means derived from the original 

 observations. In the present, and in nearly all the other cases, 

 the difference between the original and revised means is under 

 ( 2 per cent, of their value. It is a very remarkable coincidenoa 



Q 



