How to obtain it. 167 
in this view of the ovum as in some others. For the same reason 
the body of the fish is not discernible, but the veins and arteries 
of the umbilical sac are very distinct. 3 is the artery which 
conveys the blood to the body, whilst 4 is the vein by which the 
same blood returns to the heart. 5 represents the vein which 
collects the blood from the capillaries or smaller veins. The 
small dots in the veins represent the blood coursing along. The 
Fig. 15. 
numerous rounded bodies (as No. 6) are the oil globules which 
supply nourishment. 
The development goes on, and the embryo requires more 
oxygen. The water supply should be gradually increased, and 
daily attention given to the picking of the ova. When picking, 
keep the lids off the boxes as short a time as possible, 'and let the 
work be done in a modified light. A few may burst and some of 
the contents emerge, turning white immediately as the water 
comes in contact with the albumen. This is an excellent time 
for looking over the grilles and picking out any “blind” eggs 
