86 



up tUe epidermis thus forming little balls, clear as glass, 

 on the apex of which are to he found widely opened guard 

 cells. In their formation, cell division is not of rare oc- 

 currence. It rmst remain doubtful, whether the "bead glands" 

 of the Ampelidsiceae may be considered as "normal" formations 

 or whether they are to be reckoned among the abnorma3- ones. 

 It is certain that lack of light and noist^ air favor their 

 production. Kie biological explanations proposed by M^ller- 

 Thtirgau and Penaig^ do not seem to me exactly satisfying. 



c» Abnormal Su cculence 



We may speak of "abnormal succulence" when, for example, 

 it is possible to make those plants form "fleshy" leaves 

 which under normal conditions, such as are characteristic of 

 leaf succulents, would develop delicate leaf blades. 



Some experiments have already proved, that it is pos- 

 sible to force upon certain plants some pecularities of suc- 

 culents by means of treatment with salt solutions. As is 

 well known, the transpiratory power of plants decreases con- 

 siderably under the influence of concentrated salt solutions. 

 Perhaps it is the dec2?eased elimination of water vapor which 

 causes hypertrophic phenomena of growth in the experimental 

 plants nourished with strong salt solutions, causing a sim- 

 ilarity in some respects to real holophytes. 



We know but little concerning this last form of hyper- 

 trophic tissue. LeSage ^ developed artificial Succulence of 

 the leaves by abundant doses of sodium chloride, especially 

 In Lepidium sativum . The cells of the mesophyll were elong^ 

 ated greatly, showing thereby the same disintegration of 

 their chlorophyll contents, as has been repeatedly described 

 for the hypertrophies of bark and mesophyll. The. statements 

 of authors, however, do iiot always agree, in Pethybridge's 

 cultures the tissues of plants treated with NaCL remained 



1. compare especially Hofmeister in loc, cit. Further , 

 IPomaschek, Ueber pathogens Emergenzen auf Ampelopsis heder- 

 acea. Oest. Bot. Zeifeg. 1879, Bd. XSIX, _p. 87. Kreuz, En- 

 twickl. d. Lenticellen an beschatteten Zweigen von Ampelopsis 

 hederacea. Sitzungsb. Akad. Wiss. Wien. 1881, Bd. LXXZII, 

 Abt.'I, p. EE8{here also Tomaschek, Oest. Bot. Zeitschr. , 

 1881, Bd. XXXI, p. 252), 



2. I&Ller-Thurgau (Perldrusen d. V,T/einstocks. ViJeinbau u. 

 Weinhanid, 1890, Bd. VIII, p. 178) sees in them organ^ pro- 

 tective against small animals. Penzig, (Ueb. d. Peldrusen d. 

 Weinstocks u, a. Pfl. Atti Congr. Bot. Ihtemaz. Geneva, 

 1892, p» 237) considers them food-bodies, which are devoured 

 "by mites or the like. 



3. Hech, e35per. s. 1. modifications d. feuilles chez 

 1- pi. maritimes. Rev. gen. de Bot,, 1900, T. II, p. 54. 



