284 J. T. PATTERSON AND H. L. WIEMAN. 



DESCRIPTION OF PLATES. 

 PLATE I. 



The figures are camera drawings made at table level. Figs. 1-5 inclusive were 

 made with 1.5 mm. Zeiss apochromatic objective and No. 12 compensating eye- 

 piece; the remaining figures were made with the same objective and No. 6 eye-piece. 



FIG. i. Resting nucleus with large nucleolus characteristic of growth period. 



FIG. 2. Early stage in prophase of uterine spindle. C, chromosomes. 



FIG. 3. Prophase showing chromosomes fully formed about the fading nucle- 

 olus. 



FIG. 4. Spindle showing typical tetrad chromosomes. S, spermatozoon. 



FIG. 5. Polar view of equatorial plate of uterine spindle showing ten chromo- 

 somes. 



