54 Popular Errors respecting Trees. 



Switzerland. The absence of these variations retards the 

 phenomenon in the west of Europe, and still more in Madeira. 



In the facts stated by M. Heer, — facts of which we previ- 

 ously had examples in the hothouse culture of tropical 

 plants, — there is a proof of that important physiological law, 

 too often forgotten by meteorologists, that the same tempera- 

 ture or the same sum of temperatures, combined with the 

 season, does not always produce the same effect upon organ- 

 ized beings. 



Every species is as it were a machine, which performs its 

 functions under the influences of external causes, modified 

 by particular internal conditions. These vary not only be- 

 tween one species and another, between one race of a species 

 and another, and even .up to a certain point between one 

 individual and another, but also between one period and 

 another, — the same heat, after the repose of vegetation, for 

 instance, not producing the same effect as in other circum- 

 stances. 



In Madeira, the Platanus occidentalis, a native of the 

 United States, loses its leaves very slowly from the middle 

 of October, or rather they gradually become yellow and fall 

 afterwards from the action of the wind and rain. The repose 

 is complete in January, February, and up to April, during a 

 period of 87 days. The Liriodendron tulipifera, also a native 

 of North America, has a complete repose of 151 days. 



The apple and pear trees generally begin to lose their 

 leaves in December. They come into flower at Funchal by 

 the 7th of April, and their fruit is collected in August. There 

 are, however, varieties of apple and pear trees which flower 

 and produce fruit twice in the year, and one variety of 

 apple is perpetually in flower and fruit. The peach trees 

 about the 4th of November already exhibit some flowers 

 amongst their leaves; they then, to the great astonishment of 

 M. Heer, continued blossoming in abundance during the 

 months of December and January, and the fruit came to 

 maturity from the 23d of February to the end of summer. 

 In February there were flowers on the upper parts of the 

 trees, and fruit below ; and it was also then the leaves were 



