lEO 



According to Tischler«s observations on tlie nematode 

 galls of the roots of Gircaea many cells of the pleroma are 

 stimulated to abnormal growth. Large, irregularly formed giant 

 cells rich in cytoplasm are produced, many of v^ich remain 

 uni-nuclear, the rest becoming multi-nuclear, figure 50 shows 

 a group of multi-nuclear giant cells from an older Circeae 

 gall. The cytoplasm of the giant cells has begun to dis- 

 appear. Figure 50 c. shows a single giant cell with numerous 

 nuclei, 50 b. isolated nuclei in one phhse of division fam- 

 itbsis by "budding"), 



Italti-nuclear giant cells occur also in other kinds of 

 galls, louihey''- found them in "crown-galls" and in root ex- 

 crescences, v/hich in America infect various woody growths, 

 apple, pear, peach, cherry, plum, chestnut, poplar, black- 

 berry, walnut, etc. According to his careful investigations 

 the disease is produced by a slime- fungus ( Dendrophaaus glo- 

 (130) bosus >^ The infected tissues are stimulated to abundant" cell 

 division; thus producing the multinuclear giant cells,. These, 

 however, do not differ so noticeably from cells normally con- 

 structed, Such as the giant cells of Heterodera galls. Giant 

 cells are usually segmented subsequently by cross-v/alls , so 

 that uni-nuclear cells are again produced, (compare fig. 51) . 

 Judging from Tourney's drawing, these differ but little from 

 the normal ones. Figure 51 shows, side by side with cells 

 still multi-nuclear, some v;hieh have been divided by segmen- 

 tation Tinto uni-nuclear elements. Subsequent formation of 

 oross-v/alls is noted also by Vuillerain and legrain for the 

 giant cells of many Heterodera galls, (loc. cit.) 



JJulti-nuclear giant cells have been found further in 

 the galls of the blood louse and in mite galls. ^ 



Giant cells very similar to those found in gall| are 

 produced also by experimental interference. PrilleuE * pro- 

 duced multi-nuclear ^lar/c cells in seedlings, which were cul- 

 tivated at an abncrmr^lly liigh temperature. The number of the 

 nuclei, however, rarol;; exceeded three. They were often ir- 



1. An inquiry into the cause and nature of crown-gall. 

 Arizona Exper. Sta. , 1900, Bull. XXXIII, p. 51, 



2. Compare also M^iller-Thurgau, 2 Jahresber. Yersuch- 

 station W&densweil. 



3. Prillieux, Etude des alterations prod, dans le bois, 

 du pommier par 1. piqures du puceron langiere, Ann, Inst. 

 Agron., 1877-1878, p. 39 (Bot. Cbl. Bd. I, p, 436). Prillieux 

 might well have been the first to observe multinuclear giant 

 cells in galls, MoUiard, Hypertrophie pathol. des cellules 

 veget. Rev. gQ^* Bot., 1897, T. IX, p. 33. Sur les modifica- 

 tions hdstol, prod, d. 1, tiges par 1' action des Phytoptus. 



C. E. Acac. Sc. Paris, 1899, T. CZXIX, p. 841. 



4. :^Hrillieux, Alterations prod. d. 1, plantes par la cul- 

 tures d. un sol surchauffe. AUH. Sc. Nat. Bot. 6°^® ^^^*» 

 1880, T. X. p, S47. 



