ON LEAVES. 479 



cal germinal spot was again prepared for in advance, by showing the 

 child the cicatricule of a hen's egg, lying like the Mediterranean basin, 

 on a globe. Thirdly, study of the systematized topography of the 

 globe constituted the best initiation into the study of all topographi- 

 cal relations, including those involved in animal anatomy, and there- 

 fore this consideration was not among the least important. Fourthly, 

 an important elementary philosophical training was obtained, as the 

 child learned to analyze into their details the largest pictures offered 

 by the globe, and to arrange these details into orders of successive 

 degrees of generalization. Great care was taken that all pictures or 

 outlines of the same magnitude, and hence visible at the same dis- 

 tance, should be studied at the same time, and not associated with less 

 conspicuous details that required more minute attention. This rule of 

 following successive degrees of generalization in geographical analysis 

 is most imperfectly observed in text-books. It imposes itself in study 

 of the relief -globe. 



\_To be continued.] 



- 



ON LEA YES. 



By Sir JOHN LUBBOCK. 



II. 



WE have hitherto been considering, for the most part, deciduous 

 trees. It is generally supposed that in autumn the leaves drop 

 off because they die. My impression is that most persons would be 

 very much surprised to hear that this is not altogether the case. In 

 fact, however, the separation is a vital process, and, if a bough is killed, 

 the leaves are not thrown off, but remain attached to it. Indeed, the 

 dead leaves not only remain in situ, but they are still firmly attached. 

 Being dead and withered, they give the impression that the least shock 

 would detach them ; on the contrary, however, they will often bear a 

 weight of as much as two pounds without coming off. 



In evergreen species the conditions are in many respects different. 

 When we have an early fall of snow in autumn, the trees which still 

 retain their leaves are often very much broken down. Hence, perhaps, 

 the comparative paucity of evergreens in temperate regions, and the 

 tendency of evergreens to have smooth and glossy leaves, such as those 

 of the holly, box, and evergreen-oak. Hairy leaves especially retain 

 the snow, on which more and more accumulates. 



Again, evergreen leaves sometimes remain on the tree for several 

 years ; for instance, in the Scotch pine three or four years, the spruce 

 and silver-fir six or even seven, the yew eight, A. pinsapo sixteen or 

 seventeen, araucaria and others even longer. It is true that during 



