346 IMPORTANCE OF REGISTERS 



cessive stages of development, which can be called 

 fixed, even in reference to epochs that have already 

 transpired: there is no fixed interval between the 

 times of their coming into leaf and flower, or be- 

 tween the time of flowering and the time of matura- 

 tion of the fruit. 



(9.) The average range of variation in respect 

 of different periodic phenomena of the above kinds 

 appears to be about a month. By average range 

 we mean an average deduced from the sum of the 

 extreme ranges in the several individual cases. But 

 of course this will greatly differ in different localities. 

 It is also observable, though just what might be 

 expected, that the range of variation is much 

 greater in respect of those phenomena which occur 

 early in the year, than of those which occur later. 

 The flowering of plants which naturally open in 

 January or February, or the first appearance of 

 animals which are torpid during the winter, may be 

 accelerated or retarded two months or more by an 

 unusually forward or backward spring : whereas such 

 phenomena as generally shew themselves at or about 

 Midsummer rarely vary, in the times of their occur- 

 rence, to anything like that extent. The conse- 

 quence is, as observed by Lord Bacon in the case 

 of flowers,* that a long winter makes the earlier 

 and later phenomena come together. The pheno- 

 mena themselves, however much they vary in their 

 respective dates, generally, as has been before ob- 

 served (2.), follow one another in the same order. 



* Nat. Hist. (edit. 7,) p. 119. 



