69 



rods is continued on a fresh nutritive substratum at 40 de- 

 ^^v®^ i*' *^® single cells grow out into long rods. In 

 other i!fords, the growth is continued, hut the divisions talring 

 place under normal conditions are suppressed and "long roo£>'' 



/«tn ^If ^^^i'^1?^ ^^^^^ °^^ hecome as long as 40 u. (Compare fi-. 



(71) 15). !Ef the culture of long rods is again subjected to a "' 

 temperature of 34 degrees C. the previously "arrested" seg- 

 mentation is retrieved, the long cells divide into a large 

 number of short rods:- the "normal" cell-form from which we 

 started is again formed. It T^rould be of great irterest to 

 learn more of the fate of probable cell-nuclei in the de- 

 scribed processes of growth and division. We will speak 

 later of different changes of the s^me bacterium under sim- 

 ilar cultural conditions. 



Future experiments will have to determine whether pos- 

 sibly the cells of the primary meristem also may be able to 

 grow out of similar abnormally large elements. As yet not 

 a case of the kind is known to me. 



Blazek, who studied the" influence ox Benaol fumes on 

 cell- division" in the root tips of Pisum vativum . 

 proved-*- that, under abnormal conditions, the nuclei 

 divide repeatedly while the division v/alls often are 

 not formed, so that multi-nuclear cells are produced. 

 If the roots are kept in a normal atmosphere, a re- 

 duction of the multinuclear cells becomes noticeable, 

 even after only two and one-half hours. According to 

 Blazek the nuclei of the cells unite with one another 

 ('72) and the cells return to the uni-nuclear normal con- 

 dition by "karyogamy". Confirmation of this seems to 

 me most desirable, 



To a certain extent, those multinuclear blast omeres, 

 the production of vtiich in "bhe eggs of echinoderms has 

 been studied by several experimenters, resemble the 

 multi-nuclear plant cells here described. I refer 

 especially to the contributions of J. Loeb.2 By the 

 action of mechanical pressure, under the influence 

 of osmotic disturbances (treatment v/ith sea-water of 

 abnormally high or low salt content) or "oy artificial 

 warming of the eggs, segmentation is omitted while 

 the nuclear division takes jts normal course. Under 

 special circumstances, segmentation can take place 

 later. 



£, TISSUES OF ETIOLATED PLAITTS o 



Plants which are cultivated in the absence of light are 

 knovm to make a "false grovrch". Falsely grovm or etiaiated 

 plants are usually characterized by the slight development of 

 their leaf-blades, and by the excessi've lengthening of their 

 internodes and petioles, 

 "■""•"—————""— ~— " — — •--•-—— ~~———— ———--———— ' — — — ^.-— — — ——__——— _ ,^ 



1. Abhandl. bohn, Akad. , 1902, Bd. Xi, Ur. 17, Review by 

 Uemec in the Bot. Cbl., 1902, Bd. XC, p. 548. 



2. Ueber Kernteilung ohne Seliteilung. Arch. f. Entwickel- 

 ungsmechanik, 1896, Bd, II. 



