374 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



a fine network, the density of which is only slightly 

 greater at the periphery than nearer the centre of the 

 cell. In Rhynchelmis, Vejdovsky figures a much denser 

 portion of the cytoplasm around the periphery with a more 

 delicate network in the interior. The nucleus is large 

 and rounded, and at this stage is situated near the centre 

 of the cell, but as the ovum matures it comes to lie nearer 

 the periphery. The nucleus is surrounded by a well- 

 marked nuclear membrane, but I have not been able to 

 identify any perforations through which the nucleoplasm 

 is in communication with the cytoplasm, such as are 

 figured by Vejdovsky as occurring in Rhynchelmis. The 

 nucleus is composed of a large number of chromatin 

 granules embedded in the usual linin network — the linin 

 stains only faintly, but the chromatin stains much more 

 deeply, and, therefore, shows up well in good preparations. 

 The nucleus contains one or more nucleoli, which 

 appear to have a different structure in different ova. In 

 all cases there is one large nucleolus which is spherical in 

 outline, and which we may describe as the "principal" 

 nucleolus.* In some cases this nucleolus has a vacuolated 

 appearance, showing one or two fairly large vacuoles, in 

 other cases it stains uniformly and appears to be an 

 undifferentiated mass of chromatin, while in yet other 

 ova it has a granular appearance (PI. V, fig. 27, p.nul.). 

 In addition to this principal nucleolus there is usually a 

 number of smaller masses which we may call " accessory " 

 nucleoli.* These are not always present, but in those 

 oocytes in which they do occur their number varies from 

 2 to 5. These accessory nucleoli very often have no 

 connection with the principal one, but sometimes one 

 large accessory nucleolus is in conjunction with the 

 principal one, forming a compound body. In this case 



* Compare Wilson's "The Cell in Development and Inheritance," 

 p. 127. 



