YELLOW FEVER.
Yellow fever never occurs in England, except when imported from the West Indies or other countries in which it is endemic. It clings to seaport towns in hot countries; and as a permanent disease is only found when the mean winter temperature is at least 68°-72° F. A frost always stops an epidemic of this disease. The germs of this disease are communicated by mosquitoes, which act as an intermediate host. Dr. J. W. Lazear, although isolated from yellow fever cases, died of it seven days after submitting to the puncture of an infected mosquito, thus proving the communicability of this disease, and entitling himself to an honoured position among scientific martyrs.