74 



in these experiments were bred specimens. They were infected by a 

 single blood-meal on suitable gamete carriers and were kept at room 

 temperature except for the periods of exposure. Controls from each 

 lot of mosquitos were kept under normal conditions for comparison 

 with the experimental specimens. The results, which are summarised 

 in a table, show that P. rivax in the mosquito host is able to survive 

 exposure to a temperature of 30° F. for a period of two days, 31° F. 

 for four days, and a mean temperature of 46° F. for 17 days. In each 

 series of experiments the recovery of the parasites was demonstrated 

 in later dissections by conclusive evidence of further development of 

 the oocysts. In a smaller series of tests the sporonts of the aestivo- 

 autumnal parasite have shown a resistance to temperature as low as 

 35° F. for 24 hours. 



Parker (J. B.). A Revision of the Bembicine Wasps of America North 



of Mexico.— -Separate, dated 10th February 1917, from Proc. U.S. 

 Nat. Mus., Washington, lii, pp. 1-155. 



This systematic paper on the Bembicine wasps contains a chapter on 

 their biology. The follo^\dng list is given of flies found in three nests of 

 Bembex spitiolae : — Winthemia i-pustulata, F. ; Pseudopyrellia corni- 

 cinia, F. ; Musca domestica, L. ; SarcopJiaga sp. ; Chrysops pudicus 

 0. S. ; C. niger, Mcq. ; C. lugens, Wied. ; Tahanus coffeatus, 

 Mcq, ; T. puniilvs, Mcq. ; T. lasiopMhahmis, Mcq., and Odontomyia 

 virgo, Wied. 



Bacot (A.). The Effect of the Presence of Bacteria or Yeasts on the 

 Hatching of the Eggs of Stegomyia fasciaia (the Yellow Fever 

 Mosquito).— J^?. Royal Microscop. Soc, London, Part I, February 

 1917, pp. 173-174. 



The eggs of Stegomyia fasciaia are laid singly, either on the surface 

 of water, or on the wet margin beside the water. Incubation lasts 

 from 30 to 40 hours, the larva being then fully developed within 

 the egg, moist conditions during the incubation period apparenth^ 

 being essential. Should the eggs remain dry during this period, 

 they retain their vitality for several months and, upon immersion, 

 hatching begins, but is often very slow. Certain stimuli, such 

 as a fall in temperature or the addition of contaminated fluid, cause 

 dormant eggs to respond by hatching. Experiments on sterilised eggs 

 in connection with these phenomena show that the greatest stimulus 

 to hatching is the introduction of living yeasts or bacteria ; hatching 

 followed the addition of a sterile autolised extract of brewer's yeast. 

 The stimulus produced by killed cultures of bacteria and sterile watery 

 extract of brewer's yeast was much more feeble, many of the resistant 

 eggs failing to hatch, but these, when treated with living yeast cells 

 or living cultures of bacteria such as Bacillus coli, never failed to hatch. 

 Sterile filtrates of bacteria were less effective than killed cultures. 

 The addition of dilute acid, sufficient to cause the same or a somewhat 

 stronger colour reaction than that produced by a bacterial culture 

 that induced hatching, was ineffective. The addition of alkaline 

 solutions was either without effect, or caused only a small proportion 

 of larvae to emerge, whereas the addition of a bacterial culture to the 

 containers caused the eggs which had failed to respond to the alkaline 



