6 



cultivated plant to the norma! wild one to be considered a disease? In any 

 case this reversion is a condition which must be combattcd as it is evidently 

 unfitted for our cultural efforts. 



In considering such examples we see that, in treating questions of dis- 

 ease, we shall have to follow two lines of work. We must naturally first 

 keep the organism's aim in sight. And this aim, which the organism derives 

 from its very origin, is to live, and in fact to live as long as possible. Every- 

 thing which has once been originated persists as the eflfect of the causes 

 leading to its production, until a stronger factor arises which disturbs the 

 fixed order and brings about other groupings of material, form and function 

 (an inseparable trinity). Kut, up to the time of interference of such a factor, 

 the developed individual, with the sum total of the forces inherent in its 

 substance, maintains its then existing order, that is, its individuality, to which 

 a generally definable age limit is set. This necessary mechanical defense of 

 its individuality against the constant attacks of exiernal factors may be 

 termed the "force of self-preservation." In following the second line, the 

 aim of cultivation, developed from the relation of the plants to human needs, 

 is an added important factor. These conditions of the vegetable organism 

 opposing our cultural endeavors will be combatted as inexpedient. But such 

 conditions need in no way threaten the existence of the individual and there- 

 fore, according to the above explanation, are not diseases. Yet they belong to 

 the province of the pathologist as disturbances which must be considered 

 and overcome. 



In limiting the conception of disease, we meet with similar difficulties in 

 double blossoms, in as much as this doubleness is due to the fact that the 

 stamens have been changed into petals and in doing this have deformed the 

 pistil. This leads to sterility. The length of life of the individual plant is not 

 injured in any way by this sterility, but, on the contrary, is actually length- 

 ened as, for example, in double petunias. But the aim of the species is 

 affected since such double blossoms are no longer able 'o produce seeds. If 

 this kind of doubling becomes general, such species must die out in case all 

 vegetative reproductive organs are missing. This variation in structural 

 development, threatening the existence of the species, however, is 

 directly sought for in cultivation and any reversion to the normal, seedbear- 

 ing form is selected out. Here indeed the aim of cultivation contradicts the 

 natural aim and pathology tries hard to overcome the natural trend opposed 

 to the momentary direction of the cultivation, although in doing this, it di- 

 rectly threatens the existence of the species. 



Such antagonisms are very numerous. In the list of cases in which 

 only individual organs become diseased, one such local disturbance can in- 

 fluence injuriously the organism as a whole, but can yet be useful to the 

 mdividual. We would call attention here to the dropping of young fruit due to 

 drought. The cultural aim is naturally interfered with but the economy 

 of the tree reaps the benefit in as much as it saves the reserve materials, 

 which would have been used in maturing the fruit. As a result of this, the 



