338 IMPORTANCE OF REGISTERS 



may be of great interest as well as value. By the 

 help of such observations, made simultaneously 

 upon a fixed number of species of plants and ani- 

 mals judiciously selected, we are enabled to dis- 

 tinguish those localities which are similarly circum- 

 stanced in respect of the phenomena to which the 

 observations relate ; and when put in possession 

 of many such localities, we can, by drawing lines 

 through them, indicate in a very expressive and 

 instructive manner, the isochronism of these pheno- 

 mena, which must be dependent upon certain condi- 

 tions of climate connected with physiological condi- 

 tions in the phenomena themselves. For instance, 

 the first flowering of particular plants occurs, we 

 know, at different times in diiferent places ; but 

 there are some places in which, in the case of 

 a given species, it occurs at the same time : lines 

 passing through such places may be called isan- 

 thesic lines. In like manner we may have lines 

 of equal leafing, or lines passing through those 

 places on which particular trees come into leaf 

 simultaneously; also lines of isochronic fructi- 

 fication. All these lines would be analogous to 

 the isothermal and other lines adopted by Hum- 

 boldt to denote places having the same peculiari- 

 ties of temperature ; and from the close connexion, 

 before alluded to (1.), between the phenomena of 

 climate and the phenomena of the vegetable king 

 dom, it would be extremely interesting to trace 

 the relation which they bear to these last lines 

 as well as to each other. We might ask whether 

 the isanthesic lines preserved any parallelism with 



