1302 Journal of Applied Microscopy 



Eismond, J. Ueber die Natur der Sogenann- The question of the significance of the 



ten Kinetischen Centren der Zellen. Anat. centrosome is one of the most promi- 

 Anz. Centralblt. fiir die Gesammte Wiss. , , . i • i , i 



Anat. Erganz. 18: 125-141,1900. "^nt among the cytological problems 



of the present day ; recently it is espe- 

 cially considered in reference to cell mechanism as it shows itself to be of 

 importance in this connection. The view generally held is that the centrosomes 

 are a distinct, granular, primary element of the cell, a permanent part of the 

 cell, and like the nucleus multiplying by self-division. Opposed to this is the 

 view of possible spontaneous origin of centrosomes. At the same time it is 

 possible the centrosome may be a cell-organ, having to do primarily with the 

 processes of division. Many authors say that the centrosome collects around 

 itself a specially active kind of protoplasm — kinoplasm- — and permeates this in 

 the form of the different achromatic threads of the nuclear division figures. 

 Further work has developed the resemblances between this " cell organ " and 

 basal bodies in ciliated cells and the blepharoplasts in the plant antherozoid. 

 The question is still whether the centrosome, the middle-piece of the spermato- 

 zoan, the blepharoplasts and the basal bodies are truly kinetic centers of the 

 cell ; whether they originate the power for such kinetic process. 



Previous work by the author has developed the view that the centrosome is 

 not a pre-formed organ in the cell, multiplying by division, but, at least in embry- 

 onic cells, more likely arises de novo and persists until changes enter into the cell- 

 mechanism to destroy the mechanical reasons for its existence. Comparing the 

 " kinoplasmic fibers " of the mitotic figures, in so far as they actually show 

 distinctly differentiated parts of the plasmatic network, with the radiating fibers 

 of pigment cell and the " muscle-threads " of the protozoan, compels the opinion 

 that these structures are somewhat similar. The special character of the 

 muscle-threads as a peculiar elastic structure acts to make them not cause con- 

 traction, but keep the body-form of the animal by their elastic property. Proof 

 of elasticity, not contractility, lies in the effect of reagents on these fibers. The 

 axial fibers coil spirally. The comparable nature of the elastic supporting 

 apparatus of Heliozoa and tissue cells can be stated as follows : In embryonal 

 cells there is, as in some tissue cells (pigment) and protozoa (Heliozoa), a 

 permanent structure which forms a support for the cell-mechanism and can be 

 considered an elastic cyto-skeleton. Considering the centrosome of embryonic 

 cells in this connection, the cause for division is apparent. The centrosome is 

 the inert central knot of this elastic skeleton and must be divided by the 

 division of the cell body. It is a passive division. The evidence from Schaud- 

 inn's work on Ancanthocysiis acukata shows clearly the origin of the centro- 

 some in the new cells, no division of the original centrosome takes place. The 

 great variations in the form of the centrosome, from small central granules to 

 large, irregular axes as long as the cell, or as vacuolated vesicles, support the 

 de twvo view, and show that the kinoplasmic apparatus near the centrosome is in 

 general a supportive structure, whose center has different space relations accord- 

 ing to the mechanical conditions involved. 



The basal bodies of ciliated cells are next considered. Cilia in most cases 

 have no power of independent motion, but are passive, often stiff cell appendages. 



