Journal of morphology . at the microsome is morecommonly found at the junctionwhere two or more cytoplasmicthreads meet, then the problemof the origin of the centrosomein the centre of the aster isgreatly simplified. Foj- the centi-eof the aster is the point wJiei-e thegreatest ntnnber of cytoplasmicfilaments meet zvith one another,and the size of the microsome pro-duce d at such a place must becorrespondingly laige. In otherwords, the microsome produced inthe centre of the aster is thecentrosome. The centrosome thus producedgives rise in turn to a new set ofcytoplasmic fibres — the spindlefil
Journal of morphology . at the microsome is morecommonly found at the junctionwhere two or more cytoplasmicthreads meet, then the problemof the origin of the centrosomein the centre of the aster isgreatly simplified. Foj- the centi-eof the aster is the point wJiei-e thegreatest ntnnber of cytoplasmicfilaments meet zvith one another,and the size of the microsome pro-duce d at such a place must becorrespondingly laige. In otherwords, the microsome produced inthe centre of the aster is thecentrosome. The centrosome thus producedgives rise in turn to a new set ofcytoplasmic fibres — the spindlefilaments. The view that thespindle fibre originates from thecentre of the aster, and not fromthe nucleus I have given glance at a series of caryokineticfigures (Fig. 3 and Fig. 4) willshow that such is really the important fact that may beobserved in this connection, is thatthose filaments produced by thecentrosome are the smooth fibreswhich are free from varicosities,at first. The observations of C. Fig. 6. The connective tissuecells frofti the lung of , centrosome; N., Nucleus;Zk., Zvvischenkorper. After : IVeue Beitrdge ziirKenntniss der Zelle. Arch. Anat. Bd. XXXVII, 1S91,Taf. XXXVIII, Fig. 12. 440 IVA TASE. [Vol. VIII. Hermann,1 Flemming^ and others on the formation of thesmall but perfect spindle at a distance of the nucleus, bearthe same interpretation, viz., the co7iversion of the uiaterial ofthe centrosome into the fibres of the spindle. On the otherhand, it may be incidentally observed here, that the forma-tion of the perfect spindle in the substance of the cell-body, at some distance from the nucleus, shows pretty stronglyagainst the view that the contents of the nucleus has any-thing to do with the formation of the spindle filaments. The view that places the microsome in the same categorywith the centrosome throws a further light on the obscurepoints connected with the formation of the cell-plate (Fig. 5,Eq. M.) and
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