524. Chronicles of Science. [ July, 
Mr. T. Sterry Hunt, of the Geological Survey of Canada, has, 
under the title ‘Contributions to Lithology,’ given an exposition of 
the theoretical considerations which he thinks should serve as a basis 
to lithological studies. He has also pointed out desirable reforms in 
the classification and nomenclature of crystalline rocks. 
Dr. John Dean has published in the Smithsonian Contributions to 
Knowledge a beautifully illustrated memoir on ‘The Gray Substance 
of the Medulla Oblongata and Trapezium.’ The object has been to 
give the topography of those parts, with illustrations from a series of 
photographs made by himself. The photographs are of two kinds, on 
albumen paper and photo-lithographs. The former are only furnished 
for private distribution, but the latter are so well executed, that all the 
essential features are preserved. Photo-lithography has now advanced 
to a high degree of perfection; but in 1856, when Professor J. W. 
Draper was making the microscopic photographs, which his work on 
Human Physiology demanded, it was found necessary to copy them by 
hand on the wood. 
