238 LILIAN SHELDON. 



sibility of fixing cell limits is rendered still more obvious by 

 the irregular arrangement of the nuclei. Traces of a chromatin 

 network, more or less distinct, are visible in most of the 

 nuclei ; the smaller ones as a rule stain more deeply than the 

 larger. 



A section of an ovum of the next stage is figured in fig. 13, 

 in it the reticulum of the protoplasmic area has become much 

 more compact, and is flattened against the surface of the egg. 

 At the same time its width laterally has increased, so that it 

 spreads over a larger surface at the periphery of the egg. In 

 fact the protoplasmic area might be described as forming a 

 flattened plate on one surface of the ovum, throughout rather 

 more than one third of its length ; the lateral edges of the 

 plate show a slight tendency to turn inwards away from the 

 periphery of the egg. A trace of the triangular shape 

 presented by the protoplasmic area in the last stage still 

 persists in a low pointed ridge which runs along the middle of 

 the plate, and projects inwards towards the centre of the ovum. 

 Fig. 14 represents the protoplasmic area, it is drawn from the 

 same section as fig. 13, but under a higher degree of magni- 

 fication. In it the protoplasm is seen to consist of a fairly 

 close reticulum^ in which the nuclei are packed very near 

 together. The nuclei themselves possess the same characters 

 as those shown in fig. 12, and like them are of various sizes. 

 There is still no trace whatever of any cell divisions, the 

 protoplasm forming a continuous mass in which the nuclei lie 

 quite irregularly. The tendency of the lateral edges of the 

 plate to turn inwards is shown in this figure. Nuclei are still 

 present scattered through the yolky part of the ovum, and, as 

 in the last stage, are more numerous towards the periphery. 

 Traces are visible of the segmented character of the yolk, but 

 this is not very clearly shown owing to the yolky part of the 

 egg having broken and fallen out to some extent in the course 

 of cutting the sections. 



Between this stage and the one now to be described there 

 is again a large gap. A transverse section through the middle 

 region of the egg is shown in fig. 15 Cj in it the appearance is 



