562 KNOWER. 



EXPLANATION OF PLATE XXIX. 



(The posterior ends of all eggs are placed uppermost.) 



Fig. I. Ventral surface of egg tipped up somewhat to show micropyles at 

 posterior end. A., anterior; P., posterior; 1-9 on each side the micropylar 

 funnels. 



Fig. 2. Optical section of egg with one nucleus, segmentation nucleus, in 

 center. Egg stained in borax carmine and viewed as a transparent object in clove 

 oil. Yolk bodies not shown in figure. The chromatin of the nucleus is seen in 

 the center of a small mass of lightly stained protoplasm : p.b., polar bodies. 



Fig. 3. Optical section of egg with two nuclei : p.b., polar bodies ; d.n.., 

 dividing nucleus, in which the chromatin is separated into two masses. 



Fig. 4. Optical section of egg with four nuclei. The nuclei are not all in the 

 same plane. A line connecting the two posterior nuclei is in a plane at right 

 angles to one joining the two anterior nuclei lying in the plane of the paper. To 

 reach this position, the axes of the spindles of the two dividing nuclei of the last 

 stage must have rotated in opposite directions. See McMurrich on Isopods for a 

 similar phenomenon (18). All the nuclei are dividing, d.n. The chromatin of the 

 polar bodies has become much fragmented,/.!^. 



Fig. 5. Optical section of egg with nine nuclei. Nuclei scattered in yolk. 

 A.xes of dividing nuclei of last stage have rotated, as before, to make angles with 

 one another. An odd nucleus shows irregularity in divisions : p.b., polar bodies. 



(All the remaining fipires of this atid the next plate are surface views.) 



Fig. 6. Ventral surface of older egg. The cells are at equal distances apart. 



Fig. 7. Surface view of right side of egg with more nuclei than the last. 

 The nuclei somewhat more numerous in the posterior half : p.b., polar bodies. 



Fig. 8. Ventral surface. Nuclei dividing, d.n., everywhere on surface. 

 Numerous pairs of just separated nuclei, s.n., show division anteriorly as well as 

 posteriorly. 



Fig. 9. Ventral surface of egg with twice the nuclei of last. More cells in 

 posterior half, due to movement that way and to multiplication. 



Figs. 10 and loa. Ventral and dorsal surfaces of egg with double the nuclei 

 of last stage. The nuclei of the posterior half of the egg are more numerous 

 than on the other end. They lie rather close together, nearly as far forward as 

 the smaller diameter. 



Figs, ii, iia, and iib. Ventral, dorsal, and lateral surfaces of an older egg. 

 In Fig. 1 1 of ventral surface, note that the anterior limit of the area ca. of rela- 

 tively closely crowded nuclei of last stage has drawn nearer the posterior pole, 

 away from the smaller diameter of the egg. 



