286 REPORT— 1903. 



of the tissue cells, such as the gut epithelium. ' Neben-nuclei,' or 

 secondary nuclei of minute size, are to be found in the germinal vesicle 

 during the growth of the egg. They stain like the chief nucleolus, and 

 are often found in close proximity to this body. Similarly staining 

 granules found in the vacuole or vacuoles of the chief nucleolus may be of 

 the same nature. These ' neben-nucleoli ' are variable in size and number. 

 They may be readily demonstrated by means of iron-hjematoxylin or by 

 the nigrosin-light-green combination. In the iron-hsematoxylin prepara- 

 tions minute black granules resembling the neben-nucleoli were found 

 scattered in the cytoplasm as well as in the germinal vesicle. Roule 

 (Ascidian ova) and others have described a migration of nucleoli into the 

 cytoplasm. Recently (1901) Schockaert ^ (Thysanozoon) and Gerard^ 

 (Prostheceracus) have noted the presence of such chromatophil bodies in 

 the germinal vesicle and their elimination into the cytoplasm. Both 

 authors employed iron-hsematoxylin, Gerard considers that these bodies 

 represent portions of waste nuclein derived from the chromatin element 

 and destined to be eliminated from the nucleus. Schockaert, on the 

 contrary, thinks that they are ' nucleolules,' which first appear in the 

 'plastin portion ' of the chief nucleolus, and are afterwards expelled into 

 the nucleus, where they form secondary nucleoli, and there dissolve. 

 According to him, they do not contribute to the formation of the 

 chromosomes. Rohde (1903) describes a chief nucleolus and numerous 

 ' neben-nucleoli ' in the egg of the cat. He thinks that the former is a 

 ' cell organ,' and that its vacuoles have a secretory significance (c/. 

 Hacker "*), while the 'neben-nucleoli,' like the ordinary nucleoli of the 

 Amphibian egg, are genetically related to the chromatin granules (nuclein- 

 korper), the two kinds of granules being mutually convertible. 



I could find no evidence in the case of Tomopteris for a relation 

 between the neben-nucleoli and the substance of the chromosomes. The 

 circumstantial evidence was rather in favour of Schockaert's view that 

 the neben-nucleoli are derived from the chief nucleolus. I could not 

 decide whether the chromatophil granules in the cytoplasm were of the 

 same nature. They were only seen in the iron-htematoxylin preparations 

 and may be artefacts. 



There is no evidence that the chief nucleolus gives direct origin to the 

 chromosomes of the first maturation figure, although several observers 

 have stated and figured such a relation in the case of other eggs. The 

 definitive chromosomes are formed apparently quite independently of the 

 chief nucleolus. I have seen nothing resembling Carney's and Hart- 

 mann's** figures of chromatin filaments emanating from nucleoli. The 

 definitive chromosomes are formed while the membrane of the germinal 

 vesicle is still intact. They arise apparently by a condensation of the pre- 

 existing chromatin by a growth and possibly a fusion of certain granules 

 along certain tracts. The granules composing the chromosomes diSer in 

 two respects from the granules of the general reticulum : — (1) they are 

 larger, and (2) they stain with methyl green, hsematoxylin, and other 

 ' basic ' dies. 



The changes in the chromatin of the nucleus from the primitive 



' Schockaert, La Cellule, 18, 1901. 

 ' Gerard, ihid. 



' Hacker, Das Keivihldsclien, seine Elemente wnd Lageverdnderwngen, i. ii. ; Arch, 

 f. m%kr. Anat, Bd. xli. xlii., Jahrg. 1893. 



* Hartmann, ' Eireifung von Asterias glacialia,' Zool. Jahr. xv. 1902. 



