106 RISEN. [VOL. I. 



The linin consists of minute granules --linosomes arranged 

 in a more or less regular network, which latter at certain times 

 supports the elements of the chromosomes. The true nucleoli 

 or linoplasts are principally agglomerations of linosomes, and 

 serve as storage reservoirs for the linin network. 



The nuclear membrane is formed apparently from linin and 

 not from cytoplasm proper. During the anaphase a false 

 nuclear membrane is formed from cytoplasm proper, but this 

 membrane is again dissolved as soon as the object for which it 

 is formed is accomplished. 



SPINDLES AND SPINDLE FIBERS. 



The following varieties may be segregated : mantle fibers, 

 polar fibers, central spindle fibers, contractile fibers, retractile 

 fibers, and fiber cones. All these fibers originate only in con- 

 nection with an archosome. The contractile fibers alone are 

 directly connected with the centriole of the archosome. All 



the other fibers and rays emanate from 

 the outer margin of the centrosphere 

 of the archosome, but do not penetrate 

 into this sphere, and accordingly are not 

 connected with the centrioles or the 

 somosphere. The material for the man- 

 tle fibers is furnished from the granules 

 and the secretions of the plasmosphere ; 



FIG. 6. An archosome consist- 

 ing of an outer centrosphere, while the material for the central spindle 

 an inner somosphere, with two ]s f urn i s h e d by the granules and secre- 



centrioles. * 



tions of the granosphere. 



The contractile fibers are those which connect the chromo- 

 somes with the archosome. They are from the beginning of a 

 different structure from any of the other fibers, being beaded 

 and highly contractile. Their structure strongly recalls that of 

 muscle fiber. 



The fiber cones are particular structures, so far not met with 

 in any other cells. They consist of bundles of fibers held to- 

 gether at one point by an accessory archosome, while the distal 

 ends of the fibers are attached to the false nuclear membrane 



