ON THE DEVELOPMENT OP AKANEINA. 59 



Lycosa, «ta tes that there is no division of the yolk before there are 

 formed eight nuclei. In the species studied by myself, the yolk 

 columns are grouped into as many masses (yolk-pyramids or rosettes) 

 as there are nuclei, from the time when there are only two of the 

 latter. 



In PI. XII, fig. 8, I have represented a section of an egg in 

 which there are two nuclei. It will be seen that the yolk is already 

 evidently divided into two masses or segments. In the lower seg- 

 ment, the nucleus is distinctly seen. In the upper, the nucleus does 

 not happen to be in the section, but there is seen the yolk-nucleus 

 (//. n). The latter does not divide and was often found even in eggs 

 of the 4 cell stage, always by the side of one of the segmentation 

 nuclei. The segmentation cavity (^seg. cav) is already present. 

 The yolk granules immediately adjoining the perinuclear protoplasm 

 are split up into small particles at whose expense the protoplasm 

 evidently seems to increase in bulk (PI. XII, figs. 8, 9, 10). This 

 process of assimilation is no doubt continued during the whole 

 process of segmentation. 



From this stage on, as the nuclei divide, the yolk masses also 

 divide, assuming characteristic rosette or pyramidal shape (PL XI, 

 fig. 2). Strictly speaking, the segmentation is not total but syncytial, 

 as the periplasm remains undivided. Nor is it entirely regular, as 

 stages with 3, 11, 22, 34, 85 &c. nuclei were found. Nevertheless 

 the nuclei, after repeated division, are distributed fairly uniformly in 

 the egg. 



As the process of segmentati(3n goes on, the segmentation cavity 

 which was already present in the 2 -cell stage gradually enlarges so that 

 iu stages represented in figs. 9 and 10 the centre of the egg is 

 occupied by a large cavity. 



Side by side with their increase by division the nuclei together 



