248 



To surmiari7.e :- In regard to their size, the cells of a 

 plant developing pathologically ard not restricted to that 

 which the norinal plant naj?- accomplish, 



g. yorra of the Cell 



The form of merabraned cells in plants Is rlEjost alv/ays 

 identical with that of their cellulose covering. The foirri of 

 ^he Xatter is determined by the manner of its production, "bj; 

 conditions of space eto^, hut especinlly by the processes of 

 surface gro\?th, which have taken |i3iaoe in the membrane. 



The growing cells of a Spirogyra thread remain cylindrical - 

 I follovr the supporters of the theory of intus-susoeption - so 

 long as the newly superimposed particles are deposited equally 

 on all sides and longitudinally between those already present. 

 When 0- copulatory branch is produced, deposits must hive been 

 made on a definite part of the cylindrical v;all, longitudinally 

 and tangent ially. All changes in form in a gro-7ing cell may be 

 traced back to the fact that either new particles of matter hBv« 

 been deposited on everj patt of the membranes, or only in places; 

 sometimes in one direction, sometimes in severs-l. 



If svtTollen, barrlr-llke cells are produced on Splrogjrra 

 threads, by the aoti&n of etJiSjfr we roust assume that new parti- 

 cles have been deposited tangent la lly and more fibundantly in the 

 middle of the cell than at the ends. Therefore, under nbnorrrl 

 conditions differently distribut'^d deposits are made on the 

 cells, v/hereby other structiires ays formed than under normal 

 conditions, 



A consideration of the deform.ed root -hrirs, fungus hyphae 

 etc. dG3cri'ged above (p. 120) is still more instructive. When 

 the hemispherical form of cell ends is persistently retained, 

 during continued growth in length, we may assugie with Reinhardt 

 floe, crt.) that the individual particles of the head are, as a 

 rule, shoved toward the outside, until they have reached their 

 ultimate position in the cylindrical mantel and that thereby 

 the deposits of new particles must be most abuigidant near the 

 long axis, gradually decreasing towards the edge, in order to 

 cease entirely in the cylindrical-mantel". Vgry marked varia- 

 tions appear under abnorraP-1 conditions, club or hall-like forms 

 are produced according to the degree to which the deposits in- 

 crease tangentially. If the part l^tng back of the tip grows 

 more strongly than the tip Itself, bowl-like forms are produced. 

 If an especially active growth takes place at several different 

 places, branched forms arise and the like. There are indeed no 

 forms x7hloh could not ^e produced by abnormal modification of 

 the surface growth, nor which, under abnormal conditions, have 

 not been found actually occurring in the objectednamed. 



(290) The epidermal cells of leaves and shoots ea well as ground 

 tissue Qiells (fig, 43) can grow out into similar forms as al- 

 ready discussed in chapter IV, 



The question as to v/hether the formal repertoire of normal 

 cells is determinative for deformations vhich a,re possible under 

 abnormal conditions, must be ansv;ered absolutely in the negative, 



•*■ GerasSimoff. Bull. Soc. Imp. Uat. Mtiscou, 1896, Kr. 3, 

 Hathansohn in Hahrb. f. v/iss. Bot., 1900, Bd, XXXV, p,6S^ 



