298 FRANZ SCHRADER. 



EXPLANATION OF PLATES 



All figures have been drawn at table level, using a camera-lucida. Tube length = 

 160 mm., 2 mm. Zeiss oil immersion objective, and No. 12 X compensating ocular. 

 No reduction has been made in the reproductions. 



PLATE I. (all figures of Pseudococcus citri). 



FIG. I. Chromosomes of the fertilization nucleus. 



FIG. 2. Blastoderm cell during early stage in the blastoderm formation. 



FIG. 3. Blastoderm cell at time when blastoderm has become complete and 

 giant cells have begun to migrate to the symbionts. 



FIG. 4. The polar nucleus. 



FIG. 5. One of two daughter cells derived from the first division of the polar 

 nucleus, i.e., one of first polar nucleus derivatives. 



FIG. 6. One of two daughter cells derived from the division of one of the first 

 polar nucleus derivatives. Four derivatives present in the egg at this time. 



FIG. 7. Telophase of the third division of the polar nucleus. Eight derivatives 

 in the egg when this division is complete. 



FIG. ?a. One of four polar nucleus derivatives with fifteen chromosomes almost 

 condensed for the next division. Cleavage cell in resting stage coming into apposi- 

 tion. 



