189 



and bark are traversed by abnormally broad cambial ravs 

 the ducts have short members, the wood-fibres wide lumina 

 and are often cross-divided and thin-walled. The bast 

 ip^n\ f**'*®^^-^? ^^^ or entirely lacking. Tubeuf found in the 

 (210) irregularly forked branches of the Caeomti witches -brooms 

 on Thujopsis, a woody structure characterized by a paren- 

 oh^mia formation, similar to that found by Wornle in the 

 galls of the Gymnosporangla, 



Acoordlng to Giesenhagen, the leaves of the fern- 

 wit ohes-Br com are distinguished frOm normal ones by a sim- 

 pler tissue structure. For Instance, the stomata are lack- 

 ing In the abnormal leaves, produced by Ta phrina laurenoia 

 OJ^ | terls ouadrlaurliftia . Tubeuf'*' also varified similar ar- 

 f estra^nt .menomena in the diseased buds of Syringa shrubs 

 bearing • witches brooms. 



In many respects, the stag head of the willows, pro- 

 duoftd by leaf-llo© ( Aphis amentloola ). are similar to wit- 

 ohes-brooms. These have often been described since Mal-g 

 phigl and were recently thoroughly investigated by Appel . 

 In them, oauliflovrer-llke, ball, or tuft-like accumulations 

 of branches are Involved, which aan become 10 to 20 cm, and 

 aore long. The branoh].ets, of which these are composed, are 

 always short and richly set with small, often somewhat 

 thickened leaves. The axes are soft and rich in parenchyma, 

 the leaves contain undifferentiated mesophyll, - therefore, 

 the characteristics of kataplasmatic galls are repeated' 

 hwe. The stag heads originate either from normal buds, or, 

 as Appel has shown single thickly massed new vegetative 

 points, produced on the pistillate inflorescences in the 

 Interior of the ovary, as well as outside the carpel - 

 leaves on the gland spots and on the stalklet of the ovary 

 and grow out to the above described abnormal branch-excres- 

 cences. On account of the adventitious character of their 

 origin, stag heads are comparable to the witches -brooms on 

 fern-fronds, which GieseriJaagen described. 



by Prosoplasmas 



* 



We will tern prosoplasmas thoe:e galls which are character- 

 ized first by the fact that their tissues, in their differentia- 

 tion, do not show the histology of arrestment -fermentations nor 

 of callus tissues, but form new kinds differing entirely from 

 the normal,- and then also by the fact that definite proportions 

 of form end size, characteristic for the species, are always 

 repeated in them. Therefore, in this external form, prosoplas- 

 mas display something- independent, well-defined, distinguished 

 obviously from the organs of the normal plant-body; something 

 "aoi'" and independent, however, is shov/n also by their inner 

 structure , 



If we compare the histology of prosoplasmr.s with thr.t of 

 the above described kataplasmas and callus-formations (in the 

 widest sense of the word) ?/e can define prosoplasmas as those 

 (hyperplastic) new formations- of plants, in which occur also 

 histological oharaGteristios other than those known as yet in 

 arrestment and callus formations . Hyperplastic tissues of this 

 '211) icind have Deen found up to the present only in the excrescences 



Die von Milben erzeugten Hexenbesen der Syringen. 

 Plugblatt. 



„ ^ Ueb. Phyto-r und Zoomorphosen, Dissertation Wurzbuyg 

 (Konigsberg), 1899, 



