332 IMPORTANCE OF REGISTERS 



of climate, combined with the varying influence of 

 different seasons. It has been observed that the 

 several stages of existence in the tiny plant-aphis, or 

 the most insignificant insect, are connected with the 

 stages of existence in the plant which nourishes it ; 

 and this plant itself, in its gradual development, 

 is in some measure the product of all the previous 

 modifications of the ground and atmosphere.* It 

 becomes therefore a most interesting study, and 

 almost forms a science in itself, to trace out this con- 

 nection, and to observe the periodic time, as well as 

 the simultaneity, whenever it occurs, of all the 

 resulting phenomena, considered relatively with each 

 other. 



(2.) Of the phenomena themselves, or the kinds of 

 facts which, in reference to these points, should be 

 attended to by the observer, we shall speak in detail 

 presently. Some of them have been already alluded 

 to in a former part of this work.f Such persons as 

 have made it their occupation or amusement to col- 

 lect and register these phenomena, have seldom failed 

 to notice in many cases a coincidence of date, which 

 is both interesting and instructive. It has been 

 found, that, however much the seasons may differ in 

 different years, the phenomena generally follow one 

 another in the same order. This indeed is what we 

 might expect, from the circumstance of any inter- 

 ruption in the time of their occurrence, due to seasonal 



* Instructions pour V observation des phenomenes periodiques, par 

 Quetelet. From this memoir some of the remarks that follow are 

 borrowed. 



t Introd. (11.) 



