84 EISEN. [Vol. XVII. 



are somewhat more stable, though it is probable that they also 

 are subjected to changes through a readjustment or rearrange- 

 ment of their granula. However, our knowledge of these 

 minute bodies is so fragmentary that a satisfactory discussion 

 of this subject will for a long time to come be impossible. 

 All that we can now say with any degree of certainty is that 

 the chromosomes, the chromomeres, the linin network, the 

 linoplasts, the two spheres, and the nuclear membrane are 

 all ephemeral structures, their granula alone being permanent. 

 The most permanent visible organized structures of the cell 

 are the chromioles, and next to them the chromoplasts and the 

 archosomal structures, but even their permanency is only 

 approximately demonstrated. 



IX. Summary. 



I. The cell structures may conveniently be divided into 

 those belonging to the cytosome, to the karyosme or nucleus, 

 and to those of the archosome. Those of the cytosome are : 

 the cytoplasm proper, the plasmosphere, the hyalosphere, the 

 granosphere, the metaplasmic secretions, the cytoplasmic mem- 

 brane, and the various fibers and spindles, except the con- 

 tractile fibers. 



The structures of the nucleus are the chromioles, the chro- 

 momeres, the leaders, the chromosomes, the chromoplasm, the 

 endochromatic granules, the linin, the linoplasts, the nuclear 

 membrane, and the chromoplast. 



The structures of the archosome are the centrioles, the somo- 

 sphere, and the centrosphere, all of which combine to form 

 archosoraes proper and accessory archosomes. 



II. The spheres are composed of at least two, probably 

 three, distinct structures, independent of each other and con- 

 sisting of different granula. These structures are the plasmo- 

 sphere, the granosphere, and the hyalosphere, each one of 

 which has a different function or functions to perform. The 

 innermost of these spheres, the granosphere, furnishes material 

 for the central spindle, and also constitutes the main dwelling- 

 place for the archosome. The plasmosphere furnishes material 



