Tinohangeable peculim ities of their living cytoplasms. Acci- 

 dental inability to react ocoTirs when, at too lov7 or too high 

 temperatures, definite reactions of the plant are left out; - 

 specific Inability to react Is shovm^by pls-nt tissues when 

 acted upon by magnetism and the Ilk© , 



If wo compare amtng themselves cells and tissues which 

 are able Jo react v;e can easily pr«ve that different l^lnds of 

 cells respond to like stimuli vlth unlike reactions. Either 

 only the intensity of the atiwulatory effect is different, or 

 the reactions also differ from one another qualitatively. If 

 we compare cells of different plant specie s with one ariot|xer, 

 we may explain this different behavior partly by the specific- 

 ally unlike conditions of their cytoplasms. If the cells of an 

 organism or of an organ display differences In their ability to 

 react, we may assume that the unlike conditions., to which the 

 cells In the organism in correspondence with their course of de- 

 velopment ate Exposed, m^y cause these dlfferenOes, Dissimilar 

 conditions not only have Intensely Influenced the cells in the 

 course of their whole development, but still act upon them even 

 tzMl at the moment of stlmulatlim and during the reaction to the 

 atitnull. 



In the following, we will consider briefly the dissimilar 

 behavior of different plants gud tissues towards the same kinds 

 of stimuli, 



TThen comparing lov;er and higher plants with one another, 

 cryptogams and phanerogams, we find that in all the arresting 

 factors exercise about the same kiijd of effect. They are, how- 

 ever, unequally capable of reactions oonsipting of abnormal 

 growth and abnormal tissue proliferations. 



The scanty develepment of wound tissues in crjrt ogams is 

 especially striking* Indeed, cases are not lacking in whioh cal- 

 lus tissue is produced but no such extensive formations have been 

 observed in them aa are produced in phanerogams in the form of 

 callus and wound-wood. In thallophytes, at times in algae and 

 thallold liverworts, when abnor»©.l processes of growth are 



"■^'our 'slight knowledge of "the "internal" stimu;ti makes it 

 very difficult fer us to judge of ability to react and anabiiity 

 to do so. We will be able to trace back in many cases the 

 omission of a reaction to the omission of some "internal stim- 

 ults, as well as ti> explain them by (accidental or specific) 

 Inability to do so. A better insight is possible for us at 

 present only in the cases, in which we have recognized definite 

 reactions as caused by definite external factors. In many of 

 the following statements, only future investigations will be afiie 

 to decide, whether they a*e instructive on the ability of the 

 cells to react, or rather on the causes of the stimulation. Also 

 the distinction between accidental and specific inability to re- 

 act can not be carried through in many cases. Hansen has shown 

 that manv yeasts lose their ability to form spores, when brought 

 back into "favorable" conditions, may be cultivated further as 

 "asporogenic races". If contimious, sporeless "races" are ac- 

 tually involved, it is a case in which "accidental" ability to 

 react, caused by increase in temperature, becomes "specific 

 inability to do so, when the unfavorable life conditions are ef- 

 fective for any length of time. 



