294 ON THE DEGENERATION 



partially increases the growth of any particular part, all 

 disproportion of size among the relative parts^ is a devia- 

 tion from the regularity of Nature, and must be consider- 

 ed as deformity ; but as it is much more common for plants 

 to be under than over fed, the monstrosities which arise 

 from the latter cause are of rare occurrence. 



Though these various irregularities and metamorphoses 

 are classed under the head of monstrosities, I am far from 

 considering them as evils : I view these changes as ad- 

 vantageous to plants, and if naturalists rank them as im- 

 perfections in the system of vegetation, they are, by the 

 beneficence of Providence, turned to such good account, 

 that we cannot but estimate them as blessings. 



We shall now proceed to consider the influence of cul- 

 ture on the diseases of plants. The botanical physician 

 must not rest satisfied with studying the symptoms of a 

 disease, for the same symptoms may be produced by very 

 opposite causes : thus, plants turn yellow if they receive 

 either too much or too little water ; and, in order to af- 

 ford a remedy, the cause of the malady must first be care- 

 fully investigated. 



Caroline. And that must be very difficult : since, in 

 examining the patient you cannot ask him any questions* 



Mrs. B. Fortunately, the diseases of the vegetable 

 kingdom are of a less complicated nature than those of 

 animals. 



The diseases of plants may be ranged under six differ- 

 ent heads : 



1. Constitutional diseases. 



2. Diseases arising from light, heat, water, air, and 

 soil, improperly applied. 



3. Diseases arising from contusions and external injury. 



4. Diseases occasioned by the action of animals on 

 plants. 



5. Diseases proceeding from the action of vegetables 

 on each other. 



6. Diseases arising from age. 



Variegated or party-colored leaves, such as those of the 

 box and the holly, are classed as constitutional diseases, 



1587. If there is too much nourishment what will be the effects) 

 1588. How does Mrs. B. consider the tendency of these irregularities'? 

 1589. How does she say the botanical physician must proceed 1 

 1590. Under how many heads may the diseases of plants be ranged! 

 1591. What is the first'? The second] The third 1 ? The fourth! The 

 fifth 1 ? The sixth! 



