112 



APPSHDIZ. 



. T ' — 



Purely formal correspondenee with Erinemn hairs already 

 described naccesitates the mention at this point of a number 

 of other hypertrophies and form-variations which are pro- 

 . ducod by the most varied causes, showing nevertheless a nat- 

 ural relationship. In the cases here suinmarized, in the 

 first place, grov/inp: cells are eonoerned, v7hich assume an 

 abnormal form under" the influence of abnormal liSe- conditions 

 In the second place, cells with ai3iOal fi-rowth 'are constantly 

 involved, root hairs, fungus -hypiiae, sipihonae, pollensaos, 

 and the like. In the third place, the same forms are re- 

 peated in all cases, even those which have been already 

 described for the Erineum hairs, Further, we xnil be able 

 to prove that the internal formation of the cell abnormally 

 formed does not vary from the normal, if we do not include 

 here the loss of cytoplasm, v^ioh cells often undergo in hy- 

 pertrophy. Regular thickenings of the wall, formation of 

 the cell-organs, such as chlorophyll grains, etc, arfe' never 

 foxind. Also, cell division never follows cell grouth, nor 

 is anything knovna of an abnormal nuclear increase, (Ehe 

 changes are therefore only of a kataplastio nature, Porma-' 

 tion of irregular cellulose accumulations is not infrequentl 



The formal similarity of the roothairs to the cylindric- 

 al Erineum hairs is forthwith obvious ; in both cases unicel- 

 lular, almost alv;ays undivided, derivations of the epidermal 

 cells are concerned. The differences between the two lie 

 especially in the fact that the root hairs are always much 

 more slender &nd often appreciably longer than the hairs of 

 Erineum |ypes, A comparison between t he two is made especial- 

 ly important by the fact that under abnormal conditions root- 

 hairs can assume the forms described above as characteristic 

 of definite felt galls; On their apices round or v/art-like 

 processes are produced, wavy rifts become visible and here 

 and there even the beginnings of ramification, 



Thorough investigations of this subject may be found 

 in the work of Fr, Schv/arz"*-, who has furnished some informa- 

 tiflin on the conditions under which abnormally formed root- 

 hairs may occur# Schwar25 experimented with nutrient salt 

 solutions of 1 to 10 per cent, "since only the osmotic effect 

 produced by the salt is concerned here, even solutions of 

 cooking s^t, calcitim or potassium nitrate may be used. The 

 plants, however, are more easily injured by these than by 

 . a solution of nutrient substances," "A concentrated solution 

 ri21) arrests the growth of the root hairs very markedly, however 

 much it may favor their growth in thickness; If the hair 

 should grow absolutely equally in. thickness, a ball v;ould 

 necessarily be produced. This occurs only rarely and in very 

 concentrated solutions (20 per cent,). On the contrary, the 

 hairs often grow normally, later their diameter is increased 

 and their form becomes distended, after this they again be- 

 come more slender until another distension is- formed. This 



1, Die Wurzelhaare d, Pfl, Tubinger Unters, Bd, I, Heft. 

 2, 1883, p, 185, Compate further, Wortmann, Beitr, z, Phys. 

 d, WaChstums, Bot. Ztg, , 1889, Bd. XLVII, p. 283 and Rein- 

 hardt, Das V/achst-um der Pil4hyphen. Pringsheim^s Jahrb, f, 

 wiss, Bot., 1892, Bd, XZIIIip V* 557, 



