282 Ma rquette, Manifestation of polarity in plant cells which usw. 
Amongst the fungi tliere is a wliole series in which centers have 
beeil found, and in some of tliem also the central body Stands out 
plainly in the resting as well as in the dividing cells. Of these 
Phyllactinia 1 ) especially deserves mention for in it not only can 
the central body be traced uninterruptedly from one cell gene- 
ration to another but its relation to tlie chromatin can be clearlv 
t/ 
followed. 
For a considerable period' 2 ) similar relations were aescribed for 
the higher plants (Phanerogams and vascular cryptogams). However. 
the investigations concerned were largely led by conceptions which 
had tlieir origin in the results obtained on the zoological side; 
they left much to be desired in regard to both perfection of 
technique and completeness of the observations. It was not iintil 
the appearance of the „Bonner Studien“ 3 ) in 1897 that an 
approximately complete account of the development of a karyoki- 
netic figure in tlie higher plants was presented. According to 
these observations a so-called „resting“ cell shows a strictly iso- 
tropic structure, neither within the nucleus nor in tlie cytoplasm 
is tliere an organ or even a region which could in any way be 
compared to a centrosome. As nuclear division approaches, übers 
appear in the cytoplasm which are at ürst arranged radially about 
the nucleus but later bend over tili they form a feit about the 
nuclear membrane so that it, lies as it were in a nest of übers. 
Then these übers draw together more distinctly in cone shaped 
groups, but, even at this time tliere is no indication as to where 
the deünitive spindle poles are to lie. The bipolar spindle arises 
from this multipolar stage, as it is called, in that tlie various cones 
unite into two which are opposite eacli other and whose' bases rest 
against each other. After nuclear and cell division is completed 
tliere apparently is no longer any trace of a polar Organization in 
tlie cell, it again presents an isotropic structure. 
Our knowledge of spindle formation was further extended by 
a large number of observers and to most widely separated species 
of the higher plants witli the result that everywliere the process 
was found essentially the same as described by Ost er hont and 
Mottier. Wliile some of these papers present a carefully worked 
out, detailed account, of spindle-formation (see for example the work 
of Mottier 011 the embryosac of Lilium 4 ) and that of allen 011 the 
x ) Harper, K,. A.: Sexual reproduction and tlie Organization of tlie 
nucleus in certain mildews. (Carnegie Inst. Washington. 1905.) 
2 ) First by Gruignard. Sur Texistence des spheres attractives dans les 
cellules vegetales. (Compt. Rend. T. CXII 1891. p. 539.) 
3 ) Jahrb. f. wiss. Bot. Bd. XXX. 1897. Especially Osterhout. Über Ent¬ 
stehung der karyokinetischen Spindel bei Equisetum, and Mottier: Beiträge zur 
Kenntnis der Kernteilung in den Pollenmutterzellen einiger Dikotylen und 
Monokotylen. 
4 ) Mottier, D. M.: Über das Verhalten der Kerne bei der Entwicklung 
des Embryosacks und die Vorgänge bei der Befruchtung. (Jahrb. f. wiss. Bot. 
Bd. 31. 1898 .p. 125.) 
