Fig. 27. — Accessories from other cells in the same cyst as figure 26. All 

 at the same stage. 



Fig. 28. — Still later stages, showing the gradual shortening and thick- 

 ening and the final straight or rod foiTti. No indication of bivalency. 



Fig. 29. — Various shapes seen among the ordinary chromosomes in the 

 last prophase. All belong to the same type, that of the cross (a), 

 and are modifications of it. XX, Places of attachment for the spin- 

 dle fibers from opposite poles. They indicate the "proximal" end, or 

 part, of the chromosome, the place where the members of the sperma- 

 togonial pair always come in contact. They also mark the ends of 

 the transverse axis of the cross. A line drawn through this axis 

 would divide the chromosome reductionally, through the opposite axis 

 longitudinally. It is divided longitudinally the first time and reduc- 

 tionally in the second division. The ends of the longitudinal axis may 

 be bent over toward each other and brought in contact, fonning the 

 rings {f, i) or the figure of 8 {g) . If not brought in contact the 

 semiclosed ring (e) or kidney and bent-rod forms may result, a, 

 Cross, simple type form, h, Ring, c, Ci'oss, ends of longi-axis bent to- 

 wards each other, d, Another view of same, e, Semiclosed ring. /, 

 Ring, g, Ring twisted in form of figure 8. h, Another cross, i. Ring 

 greatly pulled out into transverse axis, j, Shows cross form among the 

 smallest chromosomes of the complex. 



Fig. 30. — Polar view of first spermatocyte metaphase. Plate viewed at 

 an angle of 25 degrees from the perpendicular. Twelve chromosomes 

 present, all visible in one section. Chromosomes No. 3 and 5 displaced 

 slightly outward for convenience in drawing. 



Fig. 31. — Idem, from same animal as above. Twelve chromosomes in 

 their exact position. The whole eleven ordinary chromosomes may be 

 seen at one focus. The accessory is nearer the upper pole and hence 

 not in the same focus as the eleven. 



Fig. 32. — Idem. Chromosomes farther advanced in mitosis than in fig- 

 ures 30, 31 and 33. 



Fig. 33. — All in exact position except No. 7, which lay partially over 

 No. 8. Note the smaller chromosomes in the center and the larger 

 ones in the outer portion of the plate. The accessory is traveling to- 

 ward the farther pole. 



Fig. 34. — A fragment of a cell. Lateral view of the metaphase, showing 

 position of the accessory at periphery of the cell-plate. One end only 

 has a spindle fiber attached. XX, Points on ordinary tetrads where 

 spindle fibers are attached. 



Fig. 35. — Another fragmentary cell, showing the same conditions. 



Fig. 36.— Idem. 



Fig. 37. — Metaphase, eleven chromosomes dividing. The accessory is 

 seen going off to one pole undivided. Chromosomes displaced some- 

 what to right and left in order to show each one more clearly. 



Fig. 38. — Anaphase of the first spermatocyte mitosis. Oblique polar 

 view. Eleven dyads at upper pole and eleven plus the accessory (No. 

 5) at the lower pole. The end of the accessory towards the plate has 

 split widely while the proximal end is still intact. 



