71 



and others, Brenner pj^ovecL "that the proportion between the 

 length and diameter of the cells v;as changed mi&re in favor of 

 of the** tangential diameter, the more moist the surrounding 

 air".-^ Often still other changes in the tissue structure 

 of specimens cultivated in moisture are combined with 

 these described, often papillae-like protuberances arise 

 in the upper epidermal cells, s braight forms are replaced 

 by such as have undulating outlines^!, and so forth. 



Ifoll^ recently called attention to the fact that 

 even under other -conditions than those effective in 

 the dark and in moist cultures the same phenomena of 



. . gTomth occur as in plants cultivated \?ithout light. 



i"^' Thus, with Uolx, we can speak of " starvation etiola- 

 tion " . if the roots of Triticum, as a result of un- 

 favorable nutriment v;hich lacks nitrogen, are length- 

 ened excessively. The organs of some plants exper- 

 ience similar abnormal effects upon i nfection by 

 parasites - to name a fe\7 instances, I will mention 

 the Euphorbiae, deformed by Ufomyces, and the Anemonae 

 infected by Pucciniae, Probably these abnormally 

 large organs are alBo composed of cells of abnormal 

 length. Very consxDicuous for instance is the en- 

 largement of the cells (epidermal) of the leaves of 

 Sempervivum infected by Endophyllum Sempervivi , which 

 grow out to an abnormal length. 



It is common to all the pathological phenomena here 

 cited , that in tliem whole organs., internodes, leaves, • 

 whole shoots, etc., everywhere undergo the Same change in 

 anatomiea,l structure; in those novv to be discussed local- 

 ized excresences of single tissue layers and olose3.y limit- 

 ed pathological areas will be recognizable in the hyper- 

 trophy. While in the tissues of etiolated plants, cells 

 are involved, which, from the :Cirst stages of their devol- 

 opffiBnt, come under the influence of abnormal conditions, 

 and continue their growth beyond the norsial boundaries, 



i. Undor the same conditions which led to the enlarge- 

 ment of the epidermal cells in Sedoir dendroideum, Brenner 

 found that their voliane decreased in S. altissimum. In 

 general, according to his experiments, in moist air, the 

 diameter of the cells of the leef , i.e. of the assimila- 

 ting and most stron£.'ly transpiring organs, was so length- 

 ened that the ■surface communicating directly with the air 

 was enlarged. In the- cells of the petiole, this lengthening 

 takes place principally in the direction of the axis, 

 (loc. cit, p. 4C..4.) 



2* Compare Brenner, loc, cit. The same undulated forms 

 occur in the "shade-leaves" (Ker. Rech. s, les. causes de 

 la structure des feuilles. Rev. Gen. de Bot. T. 17,1892, 

 p. 481)"; Vesque made explanatory experiments (see especial- 

 ly S. les. causes et sur les limites des variations de 

 structure des vegetans. Ann. agon. T. IX, 1884, p. 481, -ff.. T.X 

 p. 14) .Further literature citations in Brenner. 



3. Ueb. d. Stiolement d. Pfl.Sitzungsber. Hiederrhein. 

 Ges. Natur- und Heilkunde, Bonn, 1901. 



