ELISHA MITCH F:LL SCIENTIFIC SOCIETY. 117 



root in succession. Tiie root also continues to enlarge so that few 

 of the galls are attached by such slender pedicles as the attachments 

 are in the case of tubercles I hav^e seen. Since the tubercles 

 vary greatly on the roots of different species* there are probably 

 cases in which it would be difficult, from an extei'nal examina- 

 tion, to say wliether the enlargements were root galls or '^tuber- 

 cles.'^ The struct ural characters arc, liowever, so very different 

 that it will not be out of place here to note briefly the chief 

 structural characters of the tubercles and give a short resume of 

 the leading opinions regarding their function. 



Very different views have been entertained from time to time 

 as to the nature and siocnificance of these tubercular swellincrs. 

 The interior of these tubercles is composed of a loose parenchym- 

 atous tissue. In the younger parts of this tissue all observers 

 agree as to the presence of strands or threads of a very plastic 

 nature, with no cross partitions, which course between and through 

 the cells, often sending siiort flask-like branches into the cells. 

 These possessing a resemblance to the strands of plaHmodki or 

 threads of certain fungi, were so regarded by Ericksson,f Kny,j 

 Frank, § Lundstrom.|| In the older parenchymatous tissue all 

 agree in observing in the plasmic contents of the cells l)acteria-like 

 bodies of variously branched forms, forked, or Y and X f )rms. 

 These were regarded by Woronin*! and others as bacteria. Brun- 

 chorst** believed the tubercles (Knollchen) were normal struct- 

 ures, and that the bodies which Woronin and others assumed 

 to be bacteria were formed by a differentiation of the plasmic, 

 protein contents of the cells into these forms, since they were 

 found to be very rich in protein matter, and not accepting them 



k 



*Sorauer. Pflanzenkrankheiten. Zweite Auflage. Erster Band, p. 743. 



tStndien ofver Leguminosernas rotknolar, Lund, 1874; Bot. Zeitiing, S. .381, 1874, cited 

 hy Sorauer, Pflanzenkrankheiten, Zweite Auflage, Erster Band, p. 744, and by Frank, 

 Krankheiten der Pflanzen, Zweite Halfte, p. G50, 1881. 



ISitzungsber. d. bot. Ver. d. Prov. Brandenburg, 28 April, 1878; cited by Sorauer (I. c). 



^Krankheiten der Pflanzen (1. c). 



IJUeber Mykodomatien in den Wurzel der Papilionaceen. Bot. Centralblatt, Bd. 

 XXXIII, pp. 159, 160 and 185—188, 1888. 



^Mem. Acad. imp. de Scienc. d. St. Petersbourg, X, 186G. Cited in Sorauer, Pflanzen- 

 krankheiten (1. c). 



**Ueber die Knollchen an den Leguminosenwurzeln. Bericht. d. Deutsclien bot. 

 Gesellsehaft, Bd. Ill, pp. 241—257, 1885. Abstract in Bot. CeiUralblatt, Bd. XXIV, pp. 

 333, 334, 1885. 



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