12 



Mary Blount. 



Fig. 6. — Transverse section of a pigeon's egg at the end of ttie period 

 of multiplication of tlie sperm nuclei. Egg taken 6:30 a. m., about 10 hours 

 after fertilization and 31 hours before laying. Note that all cells are still 

 continuous with the yolk. 1. Accessory cleavage around the sperm nuclei. 

 2. Marginal cells sharply separated from the sperm nuclei. 3. Central cells. 

 4. Sperm nuclei. 



Fig. 7. — The left side of the section shown in Fig. 6. ac, accessory 

 cleavage, cp, central periblast, mp, marginal periblast, mc, marginal cell, 

 sn, sperm nucleus. Leitz, 5/4. Tube length, 140 mm. 



Fig. 8. — Diagram of Fig. 7. The nuclei are reconstructed from eight 

 successive sections. The nuclei in the accessory cleavage and in the marginal 

 and central periblast are derived from supernumerary sperm nuclei, ac, 

 accessory cleavage, cp, central periblast, mc, marginal cell, mp, marginal 

 periblast. 



