No. I.] SPERMATOGENESIS OF BATRACHOSEPS. ^^-J 



new nucleus, and the first appearance of the linin in the new 

 nucleus is found close to the new chromosomes. 



This new linin is, to begin with, of limited quantity, and 

 it appears as if it were actually re-formed, probably from 

 some linin granules with a generative function. In such 

 case the majority of the linin granules are either absorbed by 

 the cytoplasm or used up in the formation of the new nuclear 

 membrane. 



The Nuclear Membrane. — The nuclear membrane has already 

 been referred to in connection with the cytoplasmic membrane 

 and cell wall. The most favorable cell for the study of the 

 nuclear membrane is the large auxocyte in the beginning of 

 the chrysanthemum stage. In this stage the new nuclear 

 membrane is being reconstituted. In case the nuclear mem- 

 brane is formed by a thickening of or by an accumulation of 

 cytoplasm, we should expect to find such cytoplasm in the 

 immediate vicinity of the place where the new nucleus is to be 

 formed. No such accumulation of cytoplasm exists at this 

 place. On the contrary, a false, or rather an accessory cyto- 

 plasmic membrane has previously been formed around the 

 nucleus, but at some distance from it (Figs. 62, 70). The 

 object of this membrane is to enable a vacuole to form, in 

 which the new nucleus can have ample space for development. 

 While this membrane is yet in existence the nuclear membrane 

 is formed around the new nucleus. As at this time there is 

 no cytoplasm between the cytoplasmic membrane and the 

 chromosomes, the new membrane must be formed of other 

 matter than cytoplasm. It is probable that this other sub- 

 stance is linin, of which there is at this time a fair supply 

 around the chromosomes. 



As to the dissolution of the nuclear membrane it is most 

 interesting to note that, at least in the auxocytes, the mem- 

 brane is dissolved only after the chromosomes have formed. 

 The spindle fibers and mantle fibers cannot, therefore, have 

 anything to do with the formation of the chromosomes. The 

 nuclear membrane always disintegrates first at those places 

 where it is first touched by the fibers of the mantle. The cen- 

 tral spindle has apparently nothing to do with the dissolution 



