CONTENTS 



The Auroral display of April 15, 1869. By J. Ennis 173 



On the production of Bractea in Larix. By Thomas Meehan.. 176 

 On variation in the Genus ^giothus. By Elliott Coues, 



A.M.,Ph.D 180 



The Law of Develoi^ment in the Flowers of Ambrosia artemi- 



sisefolia. By Thomas Meehan 189 



Biological and Microscopical Department 9 



Description of Machine for Grinding Sections of Hard Sub- 

 stances for Microscopic purposes. By Coleman Sellers... 11 

 Remarks on a variety of Desmids. By H. C. Wood, M.D... 15 



