142 THE CANADIAN NATURALIST. [June 



result is, that tlie earth beyond the limits of the shadow being 

 strongly illuminated, acts as an independent source of light, and 

 this being reflected by the air, becomes polarized in planes 

 perpendicular to the horizon." These results are so diametrically 

 opposed to those previously obtained, that their accuracy is sure 

 to be called in question. 



The discrepancies in opinion of the different observers of the 

 corona, in the late eclipses, are in striking contrast to the accord- 

 ance of their observations of the protuberances. To the corona 

 attention must chiefly be directed in future, the main points as to 

 the constitution of the protuberances having been determined. 

 No means of examining it, except during an eclipse, have yet been 

 proposed ; so that unless some method of doing so is devised in 

 the interim, we must wait for the intervention of the moon before 

 we can be sure what that beautiful crown of light is — whether it 

 is composed merely of the rays which issue from behind the moon 

 as we see them radiate from behind a cloud when it obscures the 

 sun ; or whether they emanate from some metal known or unknown, 

 forming an extremely attenuated atmosphere beyond the hydrogen 

 envelope ; or whether they are identical with the auroral or the 

 zodiacal light, whatever they may be. 



CANADIAN DIATOMACEiE. 



By "William Osler, 

 [Of the Toronto School of Medicine.] 



Among the many beautiful objects which the microscope 

 has revealed to us, none, perhaps, are such general favourites, 

 (especially with the younger microscopists,) as the Diatoraaceae. 

 Their almost universal distribution — the number of species — 

 and above all, the singular beauty and regularity of their mark- 

 incrg — have all tended to make them objects of special interest 

 and study. In the following paper I propose to give, briefly, the 

 principal points connected with their life, history, and structure, 

 to^'cther with a list of those species I have met with in Canada. 



Standing, as they do, upon the very border-laud between the 

 animal and vegetable kingdoms, it is not to be wondered at that 

 the earlier observers, unable to free their minds from the idea of 



