MORTALITY IN PIKE-PERCH EGGS IN HATCHERIES. 5 
abnormal. Eggs showing normal cleavage are shown in figures 2 and 
3. Extreme variations, such as are shown in figures 4 to 10, in 
size of cleavage cells were found in nearly all cases to be correlated 
with internal conditions which presaged embryonic death sooner or 
Figs. 11 to 17.—Sections of pike-perch eggs. Magnification, approximately x 200. 
Fic. 11.—Horizontal section of a normal egg of 64 or more cells. 
Fig. 12.—From a 29-hour egg showing cytasters and abnormal spindles. 
Fic. 13.—From a 29-hour egg showing size variation in cytasters. 
Fig. 14.—From an 8-hour 15-minute egg, showing elongated nucleus. 
Fig. 15.—From a 29-hour 15-minute egg, showing partial segmentation. 
Fic, 16—From a 29-hour 15-minute egg showing degeneration in chromatin and multi- 
plication of chromosomes. 
Fic. 17.—From an 8-hour 15-minute egg showing monaster. 
later. The number of such abnormal eggs increased steadily with 
age, ranging from 1 per cent at 4 hours 30 minutes to 21 per cent 
at 19 hours. As the curve in figure 1 shows, this increase runs 
parallel with a decrease in the number of unsegmented eggs, which 
suggests the possibility that such abnormal cases are derived chiefly 
