396 THE POPULAR SCIENCE MONTHLY. 



(b) Color and general condition of the bark. 



(c) Character of the new growth. 



(d) Condition of the fruit. 



(e) Presence of parasites. 



We can not hope to correctly determine the nature of diseases by 

 seeking new light upon strictly botanical grounds alone — e. g., by 

 assuming that they originate more or less directly in fungoid growths. 

 Nor can we hope to get at the origin and cure of these disorders 

 from a purely chemical stand-point. The two lines of inquiry must 

 be followed together until they merge in one harmonious result. In 

 such manner alone may we hope in the future to solve the difficult 

 problems now awaiting the patient student, to whom they will bring 

 abundant reward. 



These thoughts are offered as a mere outline of the direction which 

 such considerations in vegetable pathology are now taking, and of the 

 form they have already assumed. 



»«» 



ADAPTATION TO CLIMATE. 



By Dr. A. BEHGHAUS. 



ANIMALS and plants are fitted by their organization to adapt 

 themselves to many changes of place and vicissitudes of cli- 

 mate. Most of the domestic plants that are cultivated in the north 

 originated in southern regions. The trees of the orange family were 

 not cultivated in Italy in Pliny's time. The citron was not raised 

 there with success till the third century ; and lemons and oranges, 

 which now grow in Southern Tyrol, not till later. The mulberry, 

 which has now made its way to Norway, likewise did not flourish in 

 Italy when Pliny wrote. Juicy peaches were not grown in Greece in 

 the time of Aristotle, and even in Rhodes the blossoms only devel- 

 oped into a thin, woody fruit ; but the peach-tree, bearing choice 

 fruit, is now common through all France, and in the gardens of Cen- 

 tral Germany. Chestnuts, originally at home only in warmer Asia, 

 are now equally so in Italy and "Western Germany. Some plants, nota- 

 bly the cereals, have enjoyed a very extensive diffusion in the course 

 of centuries, and are now cultivated in nearly every part of the habit- 

 able earth. Our domestic animals, which mostly came from Asia, 

 have gone with man to all the quarters of the world ; and it is worthy 

 of note that it is just those cereals and domestic animals that have 

 proved themselves most useful to man, and are essential to civilized 

 life, that pre-eminently possess the faculty of adapting themselves to 

 all climates, and of producing the most diversified varieties. 



The power of adaptation to climates appears to be most highly 



