PATHOLOGIC PLANT ANATOMY 355 



of the cells concerned remains similar to that of the normal ones, or is 

 altered in some way. 



(c) The increase of a part by an increase in the number of its indi- 

 vidual structural elements is known as Hyperplasia (wep = over, 

 excessive; TrXoo-ts = formation, structure), and this depends on cell 

 division following cell growth. A large number of abnormal formations 

 arise through hyperplasia and the histology of the newly formed tissues 

 is exceedingly varied. 



3. The processes of Restitution consist in the restoration of 

 structures, which resemble those lost in injuries and mutilations of the 

 plant body. Although the tissues thus formed are like the normal 

 ones yet their formation following injuries, or mutilations, comes within 

 the realm of pathologic anatomy. 



Hence we shall treat of morbid anatomy under the five heads 

 suggested in the above considerations. Naturally the material for 

 our investigation and treatment arranges itself into five chapters, on 

 "Restitution," "Hypoplasia," "Metaplasia," "Hypertrophy" and 

 "Hyperplasia." 



RESTITUTION 



Following a wound or other injury or the removal of a plant part, 

 the organs are stimulated to renew the lost part, or to repair the damage 

 to the cells or tissues. The regeneration of lost or injured plant cells, 

 tissues, or organs, is called specifically in pathologic plant anatomy 

 restitution, wHile the word regeneration, although implying restitution 

 (L. restitutio (-n), < restitutus, pp. of restituo, restore, < re-, again, + 

 statuo, set up, < sto, stand), is used in a somewhat different sense. 



The process of restitution, it is conceivable, includes a number of 

 distinct operations.^ The newly formed parts are formed at the place 

 of amputation and are like the lost portion (as the regeneration of root 

 tips) or the newly formed parts, which resemble the lost ones, are not 

 produced at the injured place, but some distance away from it, or the 

 new parts arise on the cut surface, but are unlike the lost part (hetero- 

 morphosis), and finally the new parts do not resemble the lost ones, nor 

 do they arise at the surface of the amputation. 



It will be profitable to discuss the two most important forms of 



* Consult Studien iiber die Regeneration v. Professor Dr. B. N^mec. Mit 18 

 Textabb. 



