303 
in the Pollen- Mother - Cells of Larix . 
evidence that the activity of the fibres is under the influence 
of a central body, or, directly at least, under that of the 
nucleus, it follows as the most plausible explanation that 
the fibres are self-motile — that is, that they are themselves 
the seat of the energy which they manifest. If, then, the 
central body, where it exists, really has the function of direct- 
ing the processes of spindle-building, this particular function 
seems, in the higher plants, to have been transferred to the 
fibres themselves. 
Other functions which have been ascribed to the central 
body — either the attraction-sphere with its included centro- 
some, or one of these parts, the sphere or centrosome, occurring 
without the other — must also be served, in the Seed Plants, 
by other organs of the cell. Such functions may be included 
under three heads : the central body has been conceived 
as furnishing a reserve supply of kinoplasm ; as serving as 
a centre for the building of kinoplasmic fibres ; and as pro- 
viding for the fibres a point of insertion — the spindle-pole. 
As to the first function, Boveri (’88) found that the attrac- 
tion-sphere, exclusive of its central granule, is a mass of 
kinoplasm which is used, wholly or partly, in the building 
of the aster. Other bodies than the attraction-sphere, how- 
ever, have been found to serve, in various cells, the same 
purpose — 1 archoplasm-spheres,’ the ‘Nebenkern’ of animal 
spermatozoa, and, as Strasburger has long contended (’00, 
pp. 124 ff., for rlsuml)) the nucleole. Watasd (’93) has sought 
to show that centrosomes, microsomes, the ‘ Zwischenkorper ’ 
of animal cells and the cell-plates of plants are all aggregations 
of a similar cytoplasmic material. The experiments of Hottes 
and Nemec show that, under the influence of stimuli which 
retard the activity of the kinoplasmic fibres, the fibrous 
substance tends to round up into bodies of various size, from 
that of granules or ‘ cyto-microsomes ’ to that of ‘ extra-nuclear 
nucleoles ’ ; and Hottes shows that at higher temperatures the 
extra-nuclear nucleoles seem to be transformed into fibres, 
while cooling checks kinoplasmic activity and induces the 
re-formation of nucleolar bodies. Nemec (’01) has shown, 
