34 founial of Comparative Ne?irology and Psychology. 



Migration of the nucleoli} — A migration of the nucleolus 

 as well as other nuclear material from the nucleus to the cell 

 body has been reported by several investigators. In the case 

 of the nerve cells, Rohde ('96-'03) observed the migration of 

 the nucleolus in the case of both lower vertebrates and mam- 

 mals. In a recent paper on the nerve cells, Rohde ('03) main- 

 tains the migration of the basophile substance from the nucleus, 

 where it exists in solution, into the cytoplasm. Levi ('96) 

 believes the neurosomes in the cytoplasm to be derived from 

 the nucleus. Levi showed this relation by the electrical stimu- 

 laton of nerve cells. In the present work, I have noticed also 

 the migration of the nuclear substance or accessory nucleoli 

 from the nucleus to the cytoplasm. This is so often seen in 

 the nerve cells at this stage of development that it cannot be 

 regarded as an artifact. The migration is always towards the 

 cytoplasmic process, no matter whether this process turns dis- 

 tally or toward the spinal cord. If the dislocation of the large 

 masses or accessory nucleoli were due to mechanical forces, the 

 knife or gravitation, or to other mechanical factors, one would 

 ■expect to see them moved towards the less resistant side, that is 

 towards uncovered side of the nucleus, as in the case of path- 

 ologically altered cells in which the nucleolus or intranuclear 

 masses escape towards the side on which the cytoplasm is least 

 abundant. Again, if such a migration were produced by the 

 knife or gravitation, as Herrick ('95) showed to be the case 

 in the ovarian cells of the lobster, one would expect to find the 

 •displacement always in the same direction in all the cells of a 

 given section, but such is not the case. Moreover, the general 

 appearance within the cells does not suggest a mechanical burst- 

 ing of the nuclear membrane. For these reasons, I believe 

 that the observations of Rohde and others are correct and my 

 own observations strongly confirm their statements. The fate 

 of the extruded granules has still to be considered. In order to 



' History of the observations on this subject in the tissue cells is given in 

 detail by Montgomery, T. H. — Comparative Cytological Studies with especial 

 Regard to the Morphology of the Nucleolus, Journ. Morphology, Vol. 15, No. 



2, I 



