Fowl pox virus from active skin lesions was established in the upper respiratory tract of normal chickens by nasal instillation and maintained for 12 successive passages. The nasal infection was not communicable by direct contact but did afford protection, for at least 6 weeks, against subsequent development of the virus in the skin.

Multiplication of the virus in the nasal passages was only irregularly attended by specific mucosal changes and was not accompanied by the vigorous counter-reaction engendered by the causal agents of roup.

The same strain of virus on propagation in embryonated eggs also survived and multiplied in the nasal tract but with somewhat reduced activity, the 34th egg transfer failing to afford complete protection. Nasal instillation in mice was followed only by a reaction in the lung from which the virus was recoverable through the 7th day.

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