19 



Geaham-Smith (G. S.). Flies in Relation to Disease (Non-blood- 

 sucking flies). — C(()nbrid<je Universilij Press, 1913. 292 pp.. 24 pis., 

 32 figs. [XOs. i)d.) 



The author claims that a very strong case has already been made 

 out for the thorough investigation of the relationship of non-biting 

 flies to disease, but he says that in order to determine with any degree 

 of certainty the part really played by flies, there is great need of a 

 large amount of epidemiological evidence, of which, at present, very 

 little is available. In order to meet the requirements of various 

 classes of readers, the author has printed those portions of this book 

 which relate to matters of general interest and importance, in large 

 type, and in them, as far as practicable, has avoided the use of tech- 

 nical terms. Those portions which concern the expert have been 

 printed in smaller type. The author devotes 35 pages to the species 

 of non-blood-sucking flies found in houses, giving a description of each, 

 together with theessential charactersby which they may bedistinguished. 

 A table is given which shows, from observations made in the 

 United States and in London, Manchester and Birmingham, that 

 Musca domestica ioxxws, 82 percent.. Fannia c«mc(/?ffm 14 per cent., 

 and other species, 4 per cent, of the flies found in houses and places 

 where food is exposed. The species described and figured are — 

 Musca domestica, L., M. eiitaetiiuta, Big., M. corviiKt, F., Calliphom 

 enjthrocepJiala, Mg., romitoria, L., Liicllia caesar, L., Pollenia riidis, 

 F., Muscina stabulans. Fall., Fannia canicularis, L., F. scalaris. F., 

 Anthomyia radicuni, L., Sarcojihaga carnaria, L., Sepsis pundvtn, 

 Mg., Piophila casei, L., Scafophaga stercoraria, L., Drosophila fenestra- 

 rum, Fall., and Scenopinns fenesfralis, L., and m each case an account 

 is given of the distribution and habits. 



A chapter is devoted to the life-history of the house-fly {Musca 

 domestica), and then follow chapters on the internal anatomy of this 

 species and the habits of adult flies, with special reference to range 

 of flight, outdoor habits, indoor habits, hibernation, etc. Another 

 short chapter is devoted to methods of observing flies in captivity, 

 and a fly cage used by the author is figured. Previous observers 

 have used large cages and have succeeded in keeping flies alive ni them 

 for several days ; the advantage of the author's pattern of cage is 

 that it IS small and easily handled, and by daily transfer to similar 

 fresh cages, he has been able to keep flies alive for more than three 

 weeks. He then discusses the ways in which flies carry and distribute 

 bacteria, with special reference to Bacillus prodigiosus. from which 

 it appears that this bacterium may be cultivated from the legs and 

 wings of infected flies for 18 hours (sometimes longer) after infectif)n. 

 They can be cultivated from the contents of the crop and intestine 

 in large numbers up to four or five days, and have been found surviving 

 in the intestine up to 18 days. Flies allowed to walk over plates 

 covered with agar-agar are capable of infecting them (probably bv 

 means of material regurgitated through the proboscis) for at least 

 seven days : they are capable of infecting sugar for at least two davs ; 

 flies fed on milk deposited infected faeces during seven days, on syrup 

 during four days, and on sputum for two days. Milk is frequentlv 

 contaminated by infected flies, whether they merely drink it or fall 

 into it. Conclusions arrived at in New York and Liverpool, from 



(C14) A 2 



