304 Allen . — The Early Stages of Spindle- Formation 
too, that In the higher plants other extra-nuclear masses, 
probably of kinoplasmic nature, sometimes occur. These 
facts, as well as the frequent appearance under normal con- 
ditions, at certain stages of mitosis, of extra-nuclear nucleoles, 
suggest that in plant-cells this function of the attraction- 
sphere is served by other organs, very probably in part at 
least by the nucleole, in part too, pefhaps, by other and less 
permanent bodies. 
The second function of the central body, that of furnishing 
a centre for the formation of kinoplasmic fibres, seems to 
be rendered unnecessary in the cells of the higher plants ; 
at least the evidence shows that spindle-formation in these 
plants may go on in the absence of a specialized organ which 
acts as a centre. It is true, we may think of a great number 
of centres of growth scattered throughout the cytoplasm ; 
but this conception is radically different from that of the 
centrosome, and is perhaps, in the present state of knowledge, 
one of little real value. On the basis of observed facts, 
it seems safe only to say that the forces involved in fibre- 
formation, instead of being centred about one or two points, 
are diffused throughout the cell. This is in harmony with 
the fact already noticed, that, after the formation of the 
fibres, their activities have no reference to any centre or to 
any limited number of centres. 
The other office of the central body, that of serving as 
a point of insertion for the spindle-fibres, seems also to be 
dispensed with in many instances. Many figures found in 
plant-cells recall the barrel-shaped polar spindles of A scar is 
(Boveri, ’87 ; Hacker, ’97). Very similar spindles are found 
by Fairchild (’97) in Basidiobolus , in which case, as in Ascaris , 
the fibre-bundles end in granules ; a barrel-shaped spindle 
is described in Spirogyra by many writers (see Strasburger, 
’88, and Mitzkewitsch, ’98) ; and among the Seed Plants, 
spindles which remain throughout their history blunt or 
barrel-shaped are described by Strasburger (’88) in the endo- 
sperm of Dictamnus ; by Mottier ’(97) in the pollen-mother- 
cell of Podophyllum ; in that of Convallaria by Wiegand (’99) ; 
