Experimental Studies on Germinal Localization. 203 



Normal Development of Patella. 



(From Acetic-Glycerine Preparations; x20o). 



I, 4-celI stage, from upper pole; 2, 8-cell stage, from upper pole, prep::ring 

 for fourth cleavage; 3, i6-cell stage, from the side (primary trochoblasts 

 shaded); 4, 32-cell stage, from the side; 5, 48-cell-stage (transitional to 56- 

 cell stage); 6, 48-cell stage (transitional to 52-cell), from upper pole; 7, 58- 

 cell-stage, from upper pole, after division of the rosette-cells and establish- 

 ment of the primary cross: 8, ctenophore-stage, about 10 hours, from upper 

 pole, primary trocboblasts ciliated; 9, 52-cell stage, from lower pole; 10, em- 

 bryo of about II hours, from the right side, showing three secondary trocho- 

 blasts in the lateral gap; 11, the same embryo from the left side; 12, portion 

 of the same, anterior view; at the opposite end are two secondary trochoblasts 

 (primary trochoblasts stippled, secondary unshaded). 



