There is some evidence that arsenic has a prophylactic effect.
All these prophylactic measures are directed against mosquitoes.
The planting of eucalyptus trees is out of favour at present, but it appears to have been successful in Portugal, not from any prophylactic virtues in the plant, but through the great absorption of moisture by its deep roots, which tends to dry the subsoil.
They also expressed the opinion that carbolic acid was a valuable agent in restraining tetanus growth when added to plague prophylactic, ' and they, therefore, thought that its omission was a grave mistake.
Their report on these points (Dec. 1904) contained the following conclusions: (1) " The Institute sees no reason to differ from the conclusions of the commission that the new prophylactic is not less efficacious than the old.