83 



protoplasmic strands. At this stage the nuclei exhibit a very 

 distinct nuclear membrane and present an appearance very much 

 like that of the nuclei of the higher plants in a stage just pre- 

 liminary to division (Figs. Ill and VIII.). The nuclei, while still 

 in this stage, take up a position in the protoplasm so as to form 

 a very regularly arranged layer, on the innermost side of it next 

 to the central space. This central space is lai-ge, taking up about 

 two-thirds of the whole space in the oogonium, and almost com- 

 pletely spherical ; it is extremely well defined by the layer of 

 granular protoplasm surrounding it. • The nuclei now enlarge still 

 more and become slightly elongated in a tangential direction. 

 The chromatin threads become more distinct and are seen to be 

 almost equal in size ; they are scattered irregularly in the substance 

 of the nucleus. The nuclear membrane now becomes invisible 

 and the chromatic threads appear to lie loosely in the protoplasm. 

 They next become arranged longitudinally in the equatorial plane 

 of the nucleus. In some nuclei a slightly-stained, somewhat cone- 

 shaped mass may be observed at each end of the nucleus. This 

 may be a spindle-figure, but it is much too indistinct to be 

 satisfactory. I have only seen it under the most careful 

 illumination and with an apochromatic objective. It is indicated 

 in Fig. IX. s, but is a little too strongly shaded. The nuclei 

 next divide into two groups of threads which separate from each 

 other to form two daughter nuclei (Fig. III. 3, 4). 



Simultaneously with these changes in the nuclei of the 

 oogonium, similar changes have been taking place in the anther- 

 idium, the nuclei of which divide up in exactly the same manner 

 and at the same time. The changes in the oogonium and 

 antheridium go on very regularly togetlier, but I have not been 

 able to observe any separation of the protoplasm of the antheridium 

 into a central and peripheral portion as in the oogonium. 



The arrangement of the nuclei in the oogonium now becomes 

 somewhat irregular. Further divisions of the nuclei take place ; 

 the nuclei at each division becoming smaller in size (Fig. X.). 

 A small number, two or three, of these smaller nuclei then pass 

 along the protoplasmic strands towards the centre of the 

 oogonium (Fig. X. n) ; the others remaining outside in the 

 peripheral layer. 



While these nuclei are passing along the protoplasmic strands 

 towards the centre, the cell-wall of the oosphere begins to form 



