406 Concerning Foot-Prints. [July, 
there is no difficulty in getting the best lenses and instruments, 
providing an American or English microscope of large size and 
complicated structure is not chosen. It will be found that those 
only who use a microscope for amusement utterly condemn the 
simple instruments, while those who make investigations and 
gather wide experience often assert that the greater the simplicity 
the better. “The European histologists I have met generally use 
a stand without rack and pinion for coarse adjustment, without 
movable stage and without movement round a horizontal axis. 
As to books, Frey’s Manual, of which there has been a trans- 
lation published in New York, is only pretty good. It came 
into general use because it was for a long time without rivals. 
There have lately appeared two little works on this subject, in 
England, one by Professor Rutherford, the other by Mr. Schaeffer, 
both of which are considered good. But by far the most im- 
portant work is Ranvier’s Traité Technique d’Histologie now 
being published in Paris,in numbers, three of which have already 
appeared. The moderate price of the book,— only twenty- 
five franes for a volume of a thousand pages, — the fullness of de- 
tail, and the superb illustrations alone are sufficient to recommend 
the work. M. Ranvier has written a treatise which will probably 
always be remembered as one of the most important and valuable 
manuals ever published, and which ought to be owned by every 
one who attempts to investigate the elementary structure of ani- 
mals. 
CONCERNING FOOT-PRINTS. 
BY I. C. RUSSELL. , 
TOE (foot-print lore) is the name which has been ap- 
plied to one of the most attractive and interesting paths of re 
search that geology has pointed out. This branch of palæontol- 
ogy} has for its object the study and interpretation of the many 
fossil foot-prints that have been found in the rocks, which were 
impressed there by the feet of animals when the material of 
which those rocks are composed was the shifting sands along 
some ancient shore. The study of foot-prints has at length been 
recognized as a distinct and important branch of palæontology> 
one which has often afforded the only means for judging of ~ 
character and structure of the ancient animals that have left no 
other records of their existence than the impressions of their teet. — 
1 From palaios, ancient ; onta, beings ; logos, a discourse. 
