444 



SCIENCE. 



[N. S. Vol. XXII. No. 562. 



stegomyice is not an animal parasite. Yeast 

 cells sometimes stimulate the coccidia in form 

 and staining reaction. 



The infection of yellow fever is in the 

 blood serum early in the disease. No ab- 

 normal elements that bear a causal relation 

 to the disease can be detected in the serum or 

 in the corpuscles with the best lenses at our 

 command. 



The infective principle of yellow fever may 

 pass the pores of a Pasteur-Chamberland B 

 filter. Particles of carbon visible with Zeiss 

 lenses pass through both the Berkefeld and 

 Pasteur-Chamberland B filters. Because the 

 virus of an infectious disease passes a Berke- 

 feld or Pasteur-Chamberland B filter it does 

 not necessarily follow that the parasite which 

 passed the filter is ' ultramicroscopic,' or that 

 it may not have elsewhere another phase in its 

 life cycle of large size. The filtration of 

 viruses may succeed or fail, depending upon 

 the character of the filter, the diluting fluid, 

 the pressure, time, temperature, motility of 

 the particles and other factors. 



The period of incubation of yellow fever 

 caused by the bites of infected mosquitoes is 

 usually three days, sometimes five days, and 

 in one authentic instance six days and two 

 hours; but when the disease is transmitted by 

 such artificial means as the inoculation of 

 blood or blood serum the period of incubation 

 shows less regularity. 



Yellow fever may be conveyed to a non- 

 immune by the bite of an infected Stegomyia 

 fasciata; but the bites of Stegomyia which 

 have previously (over twelve days) bitten cases 

 of yellow fever do not always convey the 

 disease. 



Fomites play no part in the transmission 

 of the disease. 



The tertian and estivo-autumnal malarial 

 parasites will not pass the pores of a Berke- 

 feld filter. 



There is a poison in the blood during the 

 chill of tertian infection which, when injected 

 into another man, caused chill, fever and 

 sweating. This poison, while present in a 

 case of tertian during the rise of temperature, 

 could not be demonstrated in the blood of a 

 case of estivo-autumnal fever during the de- 



cline of the paroxysm. While this poison 

 reproduced the symptoms of the disease, still 

 the data are too limited to consider it the 

 malarial toxin. 



Stegomyia fasciata is a domestic insect. It 

 is most active during the day, but will bite at 

 night under artificial light. The female lays 

 eggs at intervals; the maximum number of 

 eggs laid by one insect observed was 101. The 

 mosquito does not always die directly after 

 ovipositing. 



Stegomyia fasciata may bite and draw 

 blood from cadavers, although the danger 

 from spreading the infection from this source 

 is remote. 



Male and female Stegomyia fasciata may 

 pass a screen containing 16 strands, or 15 

 meshes to the inch, but not one of 20 strands, 

 or 19 meshes to 'the inch. 



Tobacco smoke produced by burning two 

 pounds per 1,000 cubic feet with an exposure 

 of two hours is sufficient to kill Stegomyia 

 fasciata. This method is objectionable on 

 account of the yellow stains and disagreeable 

 odor. Pyrethrum burned in the proportion of 

 one pound per 1,000 cubic feet with an ex- 

 posure of two hours will stupefy Stegomyia 

 fasciata; it requires two pounds to kill them 

 outright. 



From the limited number of experiments 

 made and from previous experiments it is 

 thought that sulphur dioxid is the best of the 

 gaseous insecticides for this purpose. For- 

 maldehyde gas is not an insecticide, and there- 

 fore not applicable. 



iiCIENTIFIC NOTES AND NEWS. 



M. Elie Metchnikoff, of the Institut 

 Pasteur, has been elected a foreign member 

 of the Brussels Academy of Sciences. 



Dr. Karl Schwarzschild, professor of as- 

 tronomy at Gottingen, has been elected a mem- 

 ber of the Academy of Sciences of that city. 



Brig. General A. W. Greely, chief signal 

 officer of the army, has completed a thorough 

 inspection of the Alaskan telegraph system. 



Dr. Otto Klotz, Dominion astronomer, has 

 just completed observations at Harvard Ob- 

 servatory for the longitude connections with 

 the new observatory at Ottawa. 



