154 



board subsequent to the fumigation. Snap traps were used, tlie 

 number varying from 20 to 140 according to the size of the vessel. 



In the treatment of superstructures, cyanide gas showed far greater 

 effectiveness, due to its greater penetrating powers, as well as toxicity. 

 Probably also the sulphur dioxide, on account of its odour, may give 

 more warning to the rats, enabling them to reach a place of safety ; 

 the cyanide on the other hand, being without physically irritating 

 properties, and having less odour, may poison them before they are 

 aware of its presence. Results showed similarly that cyanide gas 

 is far the more effective in the fumigation of loaded holds. 



Judging from the results of these observations it would appear 

 that the fumigation of engine and fire rooms can, under ordinary 

 conditions, be omitted without materially reducing the effectiveness 

 of the destruction of rats on vessels, since the omission of this extra 

 fumigation — carried out at the cost of increased detention of the vessels 

 and delay in relighting the fires and getting up steam — resulted in 

 the escape of only 1| per cent, of the rodent inhabitants. In excep- 

 tional cases, such as when demonstrable plague infection exists on 

 board, the engine and fire rooms should be included in the treatment. 



Carter (H. R.). Breeding of Anopheles quadrimaculatus in Deep 

 Water at a Distance from Shore. — U.S. Public Health Repts., 

 Washington, D.C., xxxiii, no. 16, 19th April 1918, pp. 571-572. 



A remarkably heavily infested breeding place of Anopheles quadri- 

 maculatus is recorded in two creeks near Quantico, Virginia, where 

 there were large masses, acres in extent, of floatage over wild celery 

 {Vallisneria spiralis). The plant was growing in water from 2^ to 

 6 feet deep and extended in places from j to | mile from shore. The 

 floatage was formed of broken blades of the plant, which rested just 

 level with the surface of the water, and was in some cases bound 

 together by a growth of algae. A camip situated about half a mile 

 from one of the creeks was heavily infested with mosquitos, as well 

 as the houses at Quantico, the source evidently being the floatage 

 in the creeks. The floatage would prevent breaking of the waves, 

 and would afford a good food supply and at the same time a complete 

 protection from fish. The problem of the control of such a breeding 

 place is a very difficult one. 



Carter (H. R,). Effect of Anopheles punctipennis on the Natural 

 Conveyance of Malarial Fever. — U.S. Public Health Repts.: 

 Washington, D.G., xxxiii. No. 16, 19th April 1918, pp. 572-575. 



Anopheles punctipennis is undoubtedly capable of conveying malaria, 

 but to what extent this species transmits the disease in nature is 

 not determined. It is not often found in houses in the day-time, 

 but it is possible that it might enter at night, feed and leave before 

 morning. It is a significant fact that malaria in the district of Mary- 

 land surveyed was reported in practically all the places where 

 A. quadrhnaculatus or A. crucians were found, while in those parts 

 where A. punctipennis alone occurred, only one house reported malaria. 

 These facts confirm observations made in many other parts of the 

 United States. While the author has never found malaria prevalent 



