B, HETEKOPIASTIC TISSUES 136 



W§ term hetero^lasia each quantitative increase of an 

 organ, in whicli, by al>tiormal cell division, tissues are pro- 

 duced, the single elements of which do not resemble normal 

 ones. Thereby either whole organs, leaves, shoots, etc.- are 

 transformed, or only parts of them, so that nevi/ tissue fcrma*- 

 tions rest like an appendage upon the mother organ. 



If the tissue of the heteroplastically changed organs and 

 parts of o-rgans be compared with corresponding normal tissues, 

 differences will be fonnd is more than one connection; the ab- 

 normal tissues vary from uormal ones in regard to size of the 

 single elements, hs well as to the degree and kind of differ- 

 entiation. 



So far as the size of the single cell is concerned, it is 

 easy to assume that to"Bnorinal increase of the cell numbers tokoB 

 place at the expense of the cell size, in such a way that single 

 elementB of hQterop;3.ftStio tissues do not attain their normal 

 size. In fact relations of this kind seem to exist In many 

 (150) cases. Hartig* observed that broad, many-celled annual rings, 

 consist of smaller (shorter) cells than' do the inner ones with 

 fewer colls. The callus, produ«ed by abundant cell division 

 after injury to living plant tissue, Is composed at times of 

 smaller cells than those of the ground tissue, etc. We shall 

 not venture to attribute especial significance to this connec- 

 tion between cell number and cell size; in a rety large numher 

 of oases the abnormal tissue is composed of larger cells, often 

 indeed aery much larger, than the normal tissue of the ground 

 tissue. 



Mtioh more important are those differences, which make evi- 

 dent the differentiation of tissue in normal end In aBnormal 

 parts. As shown above, we sliall "be concerned with some tissues, 

 which are more simtjly constructed than the corresponding normal 

 tissues and with others in whichw© may recognize processes of 

 differentiation In the formation of their single cells and the 

 distribution of their different elements; which processes of 

 differentiation, however, are not manifest in the de"Kelopment 

 of the: corresponding normal tissue. We will term heteroplastic 

 tissues of the first kind kataplasmag. those of the second 

 prosoplasmas . 



Kataplasmas and prosoplasmas are not only dittinguishable 

 on the basis of an histological consideration, but are charac- 

 terized also as Independent groups by their external form . 

 Kataplasmas show no constant proportion of size and form, the 

 same abnormal tissues occur now as deformations of the whole 

 organs, now as localized excrescences. In prosopXasmas, how- 

 ever, we find the "diseased appearance" always characterized 

 by the definite size and form of the tissue excrescences; forms 

 conspicuous because d? a liigh, ever recurring organization, ere 

 not at all rare. The difference in form is connected most 

 closely with the developmental period of the heteroplastic tis- 

 sues. We find many kataplasmas of wnich the developmental per- 

 iod vacillates within very wide boundaries, in many cases we 

 speak of it as (theoretically) unlimited. In prosoplasmas, 

 however, the duration of the development of each single foim 

 may be most exactly determined as to weeks and pionths. The 

 differences, named, for their part, may be explained, at least 

 in a measure, by theetiology of the various abnormal tissues, 

 which are partly caused by long persistent or permanent stimuli, 

 partly by stimuli of a short duration constantly effective. 



1 Holzuntersuehungen, Altes and Keues, 1901. 



