63 



oiling, draining of streams and administration of quinine to the 

 European and native population, proved highly successful at the very 

 low cost of about £20 a year. 



ScHAEDEL (A.). Biologische Betrachtungen zur Frage der Malaria- 

 rezidive und der Malariaverbreitung. [Biological considerations 

 on the Question of Malarial Relapses and the Spread of Malaria.] 

 Biol. Zentralbl, xxxviii, 1918, p. 143. (Summary in Arch. f. 

 Schiffs- u. Troih-Hyg., Leipzic, xxiii, no. 11, June 1919, p. 228.) 



The author confirms the previous results obtained by Lenz [R.A.E., 

 B, vi, 57]. At Mayence he found amongst 375 relapse cases in 

 1916 and 1917 that* the relapse curve corresponds with that of the 

 average annual temperature. High temperature, dry air, few clouds 

 and strong sunlight are correlated with a large number of relapses. 

 The maximum relapse period was, however, in June, a month before 

 the maximum temperature. Schaedel accepts Schaudinn's theory 

 of parthenogenesis of gametes and assumes that increased stimulus 

 to the gametes causes a more rapid occurrence of the relapse. 



Anopheles macidipermis is widely distributed in the Rhine region 

 from Basle to Bingen ; A. bifurcatus also occurs. Ziemann states 

 that no Anophelines occur in the fortified area of Mayence, though 

 they are common in the endemic malarial area of the Mayence basini 

 The author believes that infection with Plasniodwm pmecox {falci- 

 parmn) cannot occur in Germany, but Muhlens (to whom the present 

 summary is due) remarks that genuine cases have been observed 

 in France and Upper Silesia and does not agree with the view that the 

 typical crescents soon disappear while the gametes of benign tertian 

 malaria are much more resistant. 



Geiger (J. C.) & PuRDY (W. C). Experimental Mosquito Control 

 in Rice-nelds.— JL Amer. Med. Assoc, Chicago, III, Ixxii, no. 11, 

 15th March 1919, pp. 774-779. 



During 1918 observations in Arkansas, extending over the entire 

 rice-growing season from June to September inclusive, showed that 

 Anopheles and Oidex were present in equal and moderate abundance ; 

 breeding was fairly uniform over the entire field, with a slight prefer- 

 ence for the more open water along embankments, beginning 10-14 

 days after flooding and continuing until late in September, when 

 it gradually diminishes. Top-minnows are usually found near the 

 embankments and water-outlets, rarely in mid-field ; predatory insect 

 larvae, principally Hydrophilvs, Dytiscus and some dragon-flies, are 

 usually abundant enough to be of some importance as a check. 



As a result of the experiments detailed here the conclusions reached 

 are that intermittent flooding as a remedial measure is probably not 

 feasible owing to the additional cost of water and to the usual impossi- 

 bility of the transference of the larvae beyond flight distance. Owing 

 to the preference of top-minnows for deeper water they are of doubtful 

 value ; nevertheless their presence means a considerable reduction 

 in mosquito larvae. Oihng by drip-can methods proved a failure, but 



