159 



7th, 8th, 9th, 10th. Alive, but refuses to sting. The weather was quite 

 cold, the last three days passed off Sandy Hook. 



12th. The phial, packed in a valiese, was sent by express to Orange, 

 N. J. ; the insect arrived nearly dead. 



13th. Dead, after thirty-one days captivity, having bitten twelve 

 times, and laid probably over two hundred eggs. 



From inquiries made on the steamer, I ascertained that mosquitoes 

 are rarely felt on board during the three or four days that the vessel is 

 detained in the port of Havana, where she lies at a distance from the 

 wharves. In New York, where the ship goes to the wharf, they are apt to 

 be more troublesome, but generally disappear soon after the vessel has left 

 the port. 



Mosquitoes are observed in, Havana all the year through, but much 

 more so from May to October. In winter they are rare when the temperature 

 falls below 70° F. Last year (1885) has been an exception to the general 

 rule. Mosquitoes, especially the diurnal species, were difficult to procure 

 throughout the summer; but became more numerous in the latter part of 

 September, October, and November. A remarkable scarcity of yellow fever 

 cases was likewise observed in the summer months, and I called attention 

 to this coincidence at one of the sessions of our Academy. In October and 

 November more cases of the disease were signalled, both in hospital and 

 private practice, than in the previous months of the year, although the 

 summer heat had been more intense than usual, and had abated toward the 

 end of September, in October and November the weather being quite mild. 



Although great differences are observed in the duration of the 

 successive phases of development of the C. mosquito, the following data 

 may be taken as a fair average: Every mosquito that stings may be 

 considered as a fecundated female, and will probably lay eggs within a few 

 days after its bite, provided it can find water upon which to lay them. In 

 water-jugs standing in bedrooms, the insect is often found depositing its 

 eggs either on the sides of the jug or upon the water. The eggs are 

 commonly hatched, producing minute wrigglers, between the second and 

 fourth day, in summer; some are delayed much longer, and those that are 

 deposited outside the water may remain a long time in the dry state 

 without losing their vitality. The wrigglers grow more or less rapidly 

 according to the nutritive material contained in the water, the temperature, 

 etc., but they probably pass into the pupa stage within twelve or fourteen 

 days. This stage is always short, not lasting more than two or three days, 

 the fully developed mosquito emerging from its aquatic case a fortnight or 

 three weeks after the egg was laid. 



From the above data it will be understood how a single infected 

 mosquito, which happens to be conveyed to a healthy locality, when the 

 temperature and altitude are appropriate, might, if my theory be true, 



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