DEHATISATION	553
FOR  USE  OF  PORT  LOCAL  AUTHORITY.

certificate. 	port op issue. 	date. 	fumioakt used 	
Deratisation
Deratisation Exemption 				
DERATISATION.
Deratisation Certificate.— The International Sanitary
Convention of 1926 made it necessary for all ships to obtain from
the Port Sanitary Authority a " Certificate of Deratisation," but
if a ship can be shown to the satisfaction of the Port Authority to
be reasonably free from rats a " Certificate of Exemption from
Deratisation " will be granted. Both certificates hold good for six
months.
The onus of keeping the ship free from rats is thrown upon the
ship. If the ship is kept free the Certificate of Exemption will be
issued, if not, then fumigation will have to be undertaken. The
certificate, when issued, must be kept on board the vessel with the
ship's papers in order that it may be produced at every port. Unless
this is done the ship will have to be inspected again with the
possibility of fumigation having to be carried out. The certificate
will be accepted by every country signing the Convention as
evidence of the ship^being free of rats.
Rats begin to breed from the age of two to three months, period
of gestation three weeks, litter eight to ten rats, very prolific. It
is estimated that the progeny of a pair of rats may reach the colossal
total of 860 in the course of a twelvemonth. There are two species,
the brown rat and the black rat. The brown species is a shore
dweller and burrows; the black rat is a climber, frequents ships and
is a plague carrier, the disease being transmitted to human beings
by fleas.
RATS  AND   MICE   (DESTRUCTION)   ACT,   1919.
The attention of Ship's Master is drawn to the following provisions of the
Act and requirements of the Local Authority:—
PROVISIONS  OF THE ACT.
 (1)	The Bats and Mice (Destruction) Act applies to a vessel as if the vessel
were land, and the Master of the vessel the occupier thereof.    Section 6 (1).
 (2)	The Local Authority may by notice served on the Master of a vessel