178 Moilier.—Nuclear and Cell Division 
go to make up the spindle are controlled in certain lower 
plants by the centrosomes as centres of force, how is it that 
the same fibres in higher plants construct a karyokinetic 
figure without centrosomes or individualized centres of force ? 
Harper (’ 99 , p. 510), in the latest of his most excellent 
papers upon certain Fungi, is inclined to the view that the 
central body in the Ascomycetes is due to the meeting 
of spindle and ray-fibres. Speaking of the spindle in the 
ascus of Lachnea scutellata, he says: ‘ The ends of all these 
spindles in the equatorial plate stage are decidedly broad 
and blunt, and the central body in which they end is flat 
and disk-shaped, as in Peziza Stevensoniana and Ascobolus. 
It stains more densely than the rays or spindle-fibres, but 
there is no indication that it is more than a denser mass of 
kinoplasm formed by the meeting of the spindle and ray- 
fibres.’ ’ 
Now there may be a question whether the ‘ central body ’ 
in the Ascomycetes is homologous with the centrosome in 
Dictyota or the other Phaeophyceae , but I am inclined to 
think that the behaviour of these bodies leaves little doubt 
as to their homology. 
In Dictyota the centrosome is certainly not formed by the 
meeting of polar radiations and spindle-fibres, for it exists 
and divides when only one set of these fibres is present, and 
perhaps also when both sets are absent, as, for example, in 
the early prophase or resting stage of the primary nucleus 
of the tetraspore mother-cell. 
With all the facts taken into consideration it seems to me 
that it is the kinoplasm which should hold the rank of mor¬ 
phological unit, and the centrosome be considered as an 
individualized part of the same, existing in that form in some 
organisms and not in others, and being the expression of 
certain activities of the living substance, which are still largely 
beyond the power of the investigator to comprehend and 
explain. It is the opinion of the writer that this view is 
more in harmony with all the facts now known in both plants 
and animals. It is also clear to me, moreover, that neither 
