258 SUMMARY or CURRENT RESEARCHES RELATING TO 



• 5 cm. thick, was now placed between the flame and the mirror, and 

 filled with the vitreous and aqueous humours from four fresh bullocks' 

 eyes, it having been previously ascertained that the same vessel filled 

 with water or concentrated solution of alum produced no visible effect. 

 The screen produced no sensible difference; within three minutes 

 after the opening of the slit to a width of only O'Ol mm., a strongly 

 marked accumulation was seen at the characteristic spot. A re- 

 petition of the experiment at a different part of the same drop pro- 

 duced the same result. The four crystalline lenses of the same eyes 

 were now also placed between the mirror and the glass vessel in such 

 a way that no light could pass except through them. The intensity 

 of the light was so much diminished that it was extremely difficult, 

 when the slit was increased to a width of • 02 mm,, clearly to make 

 out the bacteria in the yellow rays ; and the lower objective B was 

 therefore used. With a width of slit of 0-01 mm., a very distinct 

 accumulation of the bacteria in the ultra-red was still visible. This 

 experiment was also repeated, with the same result, in a different 

 part of the same drop. Finally, the four corneas were also inserted. 

 Although still moderately transparent, they nevertheless con- 

 siderably diminished the intensity of the light; yet with a width of 

 slit of from O-Ol-U-02 mm. there was still a distinct accumulation 

 of bacteria. The reaction was so strong that it was evident that, 

 with the normal transparency of the corneas, it would not be per- 

 ceptibly weaker than without them. 



The author considers it certain that these reactions do not, like 

 the photokinetic movements of Navicula or Paramcecium, depend 

 simply on changes in the tension of oxygen. They resemble more 

 closely the movements of Euglena, inasmuch as they depend on sen- 

 sitiveness to light, but are more complicated. They display most 

 resemblance, however, to the sensitiveness of the eyes of higher 

 animals. 



Crystallizable Substance produced by a Bacterium.* — U. Gayon 

 describes a bacterium, smaller than B. Termo, obtained from milk or 

 from the bouillon of veal or chicken. When this bacterium is sown 

 in a vessel containing pure milk, it rapidly becomes of a yellowish- 

 green colour, its caseum coagulates, and at the end of some days 

 green crystals appear on the walls of the vessel, especially near the 

 air. With neutral bouillon of chicken, a beautiful green dichroic 

 fluid is obtained, from which the crystals separate with difficulty. 

 The crystals are insoluble in water, soluble in alcohol, ether, benzin, 

 bisulphide of carbon, chloroform, ammoniaj acetic acid, &c. 



Algse. 



Reduction of Sulphates by Algae.f — A. lEtard and L. Olivier 

 state that a microscopic examination of Becjfjiatoa, which is especially 

 abundant in sulphurous waters, shows that the protoplasmic mass of 



* Bull. Soc. Bot. France, xxviii. (1881) p. 321. 

 t Comptes Eendus, xcv. (1882) pp. 846-9. 



