203 



tl^ir^?L'TSi?i:;.ent\f ^^iee?"*'.'' t. investigate exactly 

 (232) t;7een the patholoScal nL f?!!^;,*^^ organic connection be- 



has been cleaned fpbeySnd Sfdonhf ^vt *^' ^^""* *^^^^^^ 

 only by a deposition of gerns a?e snr,.S^r?T* explained 

 beginning finlis s>, «««+ 1 t suppressed from the very 



far and o-in n^^^lt^H^ ^ ^^^ °^*^^ ^^ transmitted very 



„4..i> t^HAcirgmg Dy infiltration, are not known as jret^. 



ctor,« nS"^^r °«>2?ist principally of connective tissue but 

 sur^^J ?«??,?Jr^ tissue and epithelium, or connective tis- 



?eLel^ m1+ ?^ iS-''^f "^ *^^ ^^^^' ^^ ''^ll ^^^^^ *he blood 

 vessels out of this discussion. In plants the erounfl i-iq- 



Is'lJ%'o."/'f^^^^J^"* ^^ *^^ formation of kseLldS"4rowth« 

 as is connective tissue in tumors. "Mixed swellings" occur 



ItlK^^'^^^'^'^^J-'^ galls, epidermal outgrowths and those of 

 jne baa^, or rather the raesophyll, uniting and forming an 

 nomogeneous whole. Thus v/e can prove at the same time that 

 in galls arising endogenously the fundamental tissue of the 

 plants can develop typical epidermis (with lenticels, hairs, 

 etc.) on its upper surface and that the cells of this epi- 

 dermis can produce derivatives in every way resembling the 

 cells of the ground tissue, ^ich in the mature galls are 

 no lo.nger distinguishable frOra the descendants of normal 

 ground tissue. Therefore, we cannot speak of a "specifi- 

 city" of the epidermis etc. in plants, in the sense that, 

 in abnormal outgrowths, only new epidermal cells v/ill be 

 furnished by the epidermis and that no epidermis can be pro- 

 duced from the fundamental tissue. As is well known in ani- 

 mal tissues, such a difference between epithelial and cam- 

 bial tissue as here described is accepted as certain biy most 

 histologists. 



The histological structure of tumors even im "mixed" 

 S7\rellings" may be cl^aracterized as very simple, when com- 

 pared with the higher ofganized prosoplasraas. No tumor is 

 knovm, which consists of characteristic tisaue zones of 

 such diversity as those of the gall products of the Cynipi- 

 des, the Diptera etc. Rather, in many tumors, the production 

 of but slightly differentiated cells may be confirmed. In 

 this, tumors correspond to callus tissues and galls termed 

 katapla.smag. In common with these, tumors may also have the 

 negative characteristic that they have no definite external 

 form nor definitte size proportions. In many tumors, as in 

 many kataplasmas, v/e may speak of theoretically unlimited 

 growth. 



^ Compare especially Ribbert, Lehrb, d. Allgem. Pathol, ! 



Leipzig, 1901. \ 



^ Infiltration growth often occurs elsev/here in the develop- | 

 mental history of plant tissues. The parasitic fungi, the "thai- j 

 lus" of the Rafflesiaceae, the haustoria of many phanerogamic ; 



parasites, grow infiltratingly oh their substratugi; infiltration ^ 

 growth occurs also, for example, in unbranched latex tubes and < 



pollen tubes, the haustoria of fembryo sacs and others. I have 

 never been able to observe that galls develop forms like haus- 

 toria at their bases; future investigations, however, may perhaps ,, 

 make known phenomena of this kind. 



