116 



the galls of different Vaucheria species, produced by a 

 rotifer f lSIotoDgnata Wern&ckii )i In the tubes of this alga, 

 terminal, or lateral, wart^lilce, pear-shaped, or spherical 

 pouches occur, which bear several horn-like outgrowths, 

 ^Compare fig. 48). Each of the galls contains a mother- 

 animal besides numerous eggs or young. 



Th.9 pollen tubes which are capable of forming similar 

 deformations should still be mentioned. In artificial cul- 

 tures, intumescent forms may be obtained. 2 



As has been stated for root-hairs and the fungus hyphae, 

 it may also be assumed that, in the Siphoneae and in pollen 

 tubes, changes ifa turgor in the^growing cell cause the var- 

 iations in form here described. 



Finally, we mast mention here the involution forms of 

 bacteria, which Bageli* first observed and named. By the 

 action of unfavorable external conditions- for example, of 

 an unfavorable nutrient medi"um, or too high temperature- 

 many bacteria, especially the vinegar bacteria gfov; out into 

 extensive diverse monstrosities. They become, long, often 

 twisted filaments, bladder or spindle-like tubes, often 

 having vravy outlines. Branched forms are also abundant, as 

 in the case Of deforced root-hairs ^ etc. Ihe bacteriods of 

 the nodules in the Leg-aminbsea6 illustrate such branched 

 forms. In short, it is the same structural-repertoire, which 



1. Compare especiall^r Rpthert, Ueb. d. Gallen der Rotatorie 

 ^otommata Werneokii auf Yaucheria Walssi n. sp, Pringsheimts 

 ^ahrb,, f, Wiss, Bot. , 1896, Bd. XZIS, p. 526. Citation 



of literature also in Trotter, la Cecidiogenesi nelle Alghe. 

 Huova Hotarisia serie 211, 1901. 



2, Of the literature I y^II name Tomaschek, Eigentiaml. Um- 

 bildung der Pollens, Bull. Soc. Imp. Hat. Moscou, 1871, T. II 

 Ihe same, Kulturen der Ppllensbhlauchzelle. Verhandl. d. Uat- 

 urforsch. Ver. Brunn, 1872, Bd. XI, Halsted. Americ. ISfatur. 

 1886, Vol. XX, p. 261. Bot. Ga?. 1887, Vol. XII, p. 139. 285, 

 Acqua, Contribuz. alia conosc. delle cellula veget. J/Ialpighia 

 1891, Vol, V, p, 3. 



3, Just as in the cell^sa-cs already described, thick and 

 thin places alternate vrt.th each other, according to whether 



-growth takes place chiefly in length or in thickness, in 

 multicellular organs, thick and thin places can follow one 

 another like a string of beads, if, in their development, 

 the external conditions alternately arrest and favor growth 

 in thickness. For roots aesembling strings of beads, com- 

 pare Sachs, Gesamm. Abhandl, , Bd, II, p. 801. 



4. ^ie nied. Pilze in ihren Bezieh. zu. den Infection- 

 krankh, 1877. 



