3io 



GEORGE W. TANNREUTHER. 



FIGS. 11-15. Different stages in the second maturation division, showing the 

 method of reduction of the chromosomes. Both micronuclei are dividing. 



FIG. 16. Micronuclei produced by the second maturation division. The 

 micronuclei are in the prophase stage of the third division. More than two 

 micronuclei seldom divide in the same conjugant. The macronuclei are in the first 

 stages of disintegration. 



FIG. 17. Two of the micronuclei in either conjugant are dividing. The others 

 are deteriorating. The macronuclei are dividing by nuclear clefts. 



FIG. 18. A single micronucleus in either conjugant is dividing. 



FIGS. 19 AND 20. Formation and exchange of pronuclei. The pronuclei vary 

 in size, corresponding to moving and stationary nuclei. 



