500 A. E. MILLER 



before mentioned of displacement outwards of the meridional 

 furrow from the abapical pole. 



Towards the end of this period the greater rapidity of the 

 segmentation at the apical pole becomes more marked, and the 

 four vertical furrows make their appearance. 



Four eggs at about stage 4 were availalile and two showed 

 similar development, two of the new furrows shoAving the 

 normal ' vertical ' position and maintaining a vertical course, 

 w^hile the other two furrows, instead of being vertical, have 

 their point of origin displaced towards the apical pole so that 



Text-fig. 4. 



Apical view. 



they have become meridional, bisecting two of the quadrants. 

 The study of sections show that all the eight nuclei are in the 

 metaphase stage of mitosis ; therefore, up at least to this 

 stage, mitosis is synchronous throughout the egg. This paper 

 is not intended to deal with nuclear phenomena, but it will 

 be of interest to show" an accurate drawing (Text-fig. 5) of a 

 nucleus from the segmenting egg of Lepidosirenas illustra- 

 ting the extraordinarily favourable nature of these nuclei for 

 cytological investigation. 



In the egg shown in Text -fig. 6 the two meridional furrows 

 are complete. On one side of the egg (that shown in the upper 

 half of Text-fig. 6) two vertical furrows are present, exactly 

 in line with one another so that they have the appearance of 



