180 



sections of shoots are brought to hyperplastic development; 

 sometjftaes more or less extensive parts of single organs. Ball* 

 like 'swellings are often produced, or isolated galls, often 

 clustered compliexes. Since the area of infection in 'the case 

 of different gall producers has no constant size, tiny pus- 

 tules are often produced or often extensive deformations, 

 corresponding to the amouDt to which the parasites are dis- 

 tributed on or in their host plants. 



The histolOi3y of kataplasmas needs no detailed descrip- 

 tion. Alnjost universally, aside from a slight tissue differ- 

 entiation, the conT>ostion of ko.taplasmas is nade up of abnor- 

 mally large cells. ■'■ As in all gall-formations the cells of 

 the kataplasmas also show an abundant albumen content. They 

 often contain red cell-^sap pigment. Especially striking is 

 the accumulation of starch which we find as^in in re^y dif- 

 ferent kinds of galls,- in the rupture of the cabbage as in 

 the tubercles of Leguninoseae roots, in aphid galls etc. Since 

 the anatomical structure of kataplas:Tias shov/s essentially 

 everywhere the same structure forms, in their slight differ- 

 entiation, it suffices to exjJlain the essential points by a 

 few ej-camples. 



. 1. P rimary tissues. 



The difference between normal and infected tissues is 

 very obvious, when leaves and parts of stalks are involved, 

 which if undisturbed, would develop diversely differentiated 

 tissues in vrell-sepax'ated layers. 



In leaves etc. infected by fungi (Mycocecidia) the other- 

 v;ise very evident difference between epidermal and ground tis- 



(199) sue cells is often only weakly defined. In the mesophyll it- 

 self the difference in formation between palisade parenchyma 

 and spongy p&renohyraa is often entirely lost. In other cases 

 a slight differenece in the cells of the upper and lov^^er meso- 

 phyll layers is retained. It is often the case that the cells 

 of the spongy parenchyma are prevalently incited by infection 

 to a rich proliferation. The illustration by Woronin, re- 

 produced here, shows very clearly the difference between 

 normal and diseased raesophyll: the parts of the leaf of Vac- 

 oiniuffi 7 iti s Ida ea infected by B yoba sidi ui>.i Y accinii are great- 

 ly disten(ied(figr'74a) developing a tissae composed of very 

 large cells, poor in chloroijhyll or :';'ree frotii it (fig. 74b); 

 the uppermost well layer of this corresponds to a hypertro- 

 phied palisade layer. The tissue continuity of the cells is 

 the same in all parts of the leaf, a difference between thick 

 and porus spongy tissue (fig.' 74b* at the left) being scarce- 

 ly recognizable in the part of the leaf infected. In some 

 cells of the gall a red coloring matter is developed. That 



(200) even the mesophjrll of the conifer needles^,may be brought to 

 excrescence by. fungi has been proved by Wornle, in the leaves 



1, It was mentioned above fp. 117) that in cases of weak 

 infection, or unfavorable developmental cosaditions, the cell 

 divisions are absent, and instead of hyperplastic excrescences 

 only hypertrophic changes can qqc^t. 



