188 How to obtain it. 
black, and, with the rapid steam communication which we have 
nowadays, they may be safely started on very long journeys at 
this stage. They are about half incubated, and, when packed in 
moss and iced, they will not hatch so soon as they would have 
done in the trays in the hatchery. The low temperature at which 
they are kept during ocean voyages slightly retards the develop- 
ment of the embryos. When packing eggs for export a few are 
invariably retained, packed in moss exactly like those exported, and 
kept at a low temperature, and these usually remain unhatched 
for fourteen days or so after the date of arrival of the consignment 
sent abroad. On being unpacked and placed in a hatching box 
they generally hatch very soon. 
I have received accounts of ova successfully sent to the 
Colonies, which have, on unpacking and being placed in the 
hatching boxes, hatched in a few hours. On one occasion a lot 
which were sent to Natal hatched off in a few minutes, the 
temperature of the water being over 60°F. This was a very 
natural result after being taken from their well-iced packing case. 
The temperature of the water was first lowered by means of ice, 
and then allowed to rise gradually. Ova can now be sent very 
successfully to any part of the world. It is not to be supposed 
that no loss takes place on these consignments. Sometimes they 
travel beautifully, and, with the well-studied system of packing 
that is now adopted, there is every chance of this, provided they 
are properly attended to during the voyage out. 
For long voyages the eggs are packed in a very similar 
manner to the one adopted for home packing, though a few extra 
precautions are necessary. An air space is left at the bottom of 
the packing case, and the perforated zinc bottoms of the trays are 
all double, a quarter of an inch being allowed between the double 
bottoms for ventilation. The zinc used is never new, but always 
well seasoned material that has been used for screens between the 
fry ponds the year before. This does not: dissolve and produce 
any salt of zinc, which is fatal to ova, and should be carefully 
guarded against. An empty tray is fitted into the box at the top, 
which is filled with ice, and kept full during the voyage, and 
should any hitch occur here, especially going through the tropics, 
all the consignment will be lost. 
