DR. GRIFFITH, ON THE MICROSCOPE. 203 
microscopic, are treated at length. Here we have an 
account of that very heterogeneous and doubtful family, the 
Infusoria. Of course in catering for juniors, Dr. Griffith does 
not indulge in speculating as to the animal or vegetable 
nature of these organisms. He gives descriptions of various 
forms, which his plates display in all their proportions and 
colours. Wisely reserved to the latter part of the book is a 
chapter on “optical principles.”” We advise all readers to 
skip this chapter if they please. A dinner is not the less 
pleasant that you are ignorant of the structure and functions 
of the nerves of teeth. The wonders of the microscope may 
be enjoyed without a knowledge of “ optical principles.” 
What we commend is the use of the microscope, and when 
observation has gone to its furthest point, the desire for a 
knowledge of the principles on which we have proceeded may 
undoubtedly lead to yet further discoveries. 
In conclusion, we would commend Dr. Griffith’s work to 
our readers, believing they will find it all that is necessary 
for the commencement of observations with the microscope. 
Should they ever become masters of its details, we can rejoice 
with them in the power they possess of diving deeper into the 
great secrets which the Creator of All has yet to reveal to 
those who diligently study and take delight in His works, 
