178 



host growa out in a ridge around the clasp shield of 

 tho parasite (Phoradendron etc) , thereby producing 

 radiated cup-like excrescences, corresponding to the 

 form 01 the paras it e.-'- 



The Zoocedidia . which may he classed among kataplasmas are 

 produced especially by worms (Nematodes) and also by mites 

 and insects, 



Nematode galls, produced by Heterodera and Tylen- 

 chus, are found on the aerial and underground parts 

 of the vary many different plants. H. radicicola is 

 important because of its "distribution; it produces 

 knob«like galls on the roots of monocotyledons and 

 dicotyledons. Nematode galls (produced by Tylenchus 

 fucicola )are said to occur also on Ascophyllum nod osum^ 



Of the mite galls, I consider as belonging here 

 the fleshy (hyperplastic) curlings of the leaf edges 

 of Tilia, Crataegus, Pirus and many others, the bud 

 swellings of Corylus aveli^an a. the galls on the tips 

 of shoots, which are compose'H! of swollen leaves and 

 the so-called pustule galls abundant on Pirus communis 

 on Sorbus and many others, many "Erineum" galls, con- 

 sisting' of multicellular cones and ridges, such as 

 the S0"calle d Briueum populinum. and still others. 



The Diptera often produce complicated galls with 

 a prosoplasmatic structure; the kataplasmas called 

 forth by them repeatedly have the form Of fleshy 

 cuiiings of the leaf edges (for example, on Polygonum, 

 Populus tremula and others) and swollen tips of shoots 

 (for example, on Glechoma) or there are produced by 

 a uniform swelling of numerous leaf bases or inflor- 

 escence stalks, clustered forms, resembling pine- 

 apples, termed pinapple-galls . Gecidia of this kind 

 have been found on various Crueiferae (for example, 

 Nasturtium, Barbarea) and others. 



1. pompare the illustrations in Engler, Loranthaceae, 

 Naturl. Pfl.-J'ara, , Bd, III, I, p. 61. 



2, Statements concerning nematode galls are to be found 

 especially in Frank, „Die Krankh. d. ^fl., 2. Aufl„, 1896, 

 Bd.„III, p. 12. C, Muller, Mitteil. ub. d. uns. Ku;|.turpfl. 

 scha'dlichen, das Geschlecht Heterodera bildenden Wurmer. 

 Landwirtsch. Jahrb., 1884, Bd. XIII, p. 1. Ritzama Bos, 

 Die Aelchenkrankheit d. Zwiebein (Allium ■ Cepa) . Landw. Ver- 

 suchsstat., 1888, Bd, IDIXV , p. 35. Atkinson, Nematode 

 Root-galls, J. Elisha Mitchell. Scient. Soc, 1889, Vol. 

 71. — Many new statements in Sorauer^s Zeitschr. f. pflan- 

 zenlsranlt^.- For 2?ylenchus fucicola compare Murray, Phyco- 

 logical Memoirs, 1892, Part I, p. 21. 



