46 MODERN FO&EST ECONOMY. 



16. ' Algeria in her turn is passing, through a crisis, out 

 of which she ought to come more vigorous; at the 

 present time she is wholly for the culture of the vine, and 

 perhaps she will yet find that evil which is expected will 

 come upon her to turn her from the way in which she is 

 advancing with such vigour ; it is a certainty that the cul- 

 ture of the vine will lead during the next few years to riches 

 hitherto unknown, and will certainly contribute in a large 

 measure to the progress of Algeria ; but it is necessary to 

 bear in mind that there is no culture more dangerous, and 

 it is not without trembling that one looks forward to the 

 ravages which the invasion of the phylloxera will occasion 

 in a country prosecuting too ardently the creation of vine- 

 yards ; the evil will be terrible, and progress will be 

 completely arrested. But Algeria rewooded and irrigated 

 is proof against every catastrophe, for all kinds of culture 

 are then open to her.' Dtherain. 



17. ' It may be said that the measure of attention given 

 to trees indicates the condition of the agriculture and 

 civilisation of a country.' Make. 



18. 'On the presence of forests on the mountains depends 

 the existence of crops, and the life of the population. 

 Here the existence of wood is no longer, as it is on the 

 plains, a question of convenience ; it is the question of 

 " to be or not to be." ' Surell. 



19. ' In a forest the mean temperature is always lower 

 than it is in a denuded country ; but the difference is less 

 marked in winter than it is in summer ; the maximum 

 temperatures are always lower, and the minimum tempera- 

 tures are always higher. In a forest the reduction and 

 increase of temperature always advances more slowly ; the 

 temperature there is always more equal in the day and in 

 the night, between one day and another, and from season 

 to season : sudden changes of temperature, if they do not 

 last long, do not make themselves felt ; from all which we 

 are warranted in concluding that forests tend to keep 

 down the general temperature of a country on the other 

 hand they tend to diminish the degree of sudden changes 



