INFUSORIAL ANIMALCULES. 41 



and injure it witliout your being immediately aware of 

 the fact. 



Section XVI. — On Microscopes for Examining Infusoria, 



A good microscope cannot be fully appreciated until it is 

 brought to the examination of living Infusoria. It is true, 

 that we may make use of the scales of insects and other 

 similar objects as tests— we may see with wonder the 

 different markings on the surface of these dust-like atoms, 

 but our admiration will be carried still higher, by the 

 development of those brilliant colours and delicate tints 

 which are discoverable in many species of the minute 

 Infusoria. The criterion of a good microscope, then, will 

 be, that not only the forms of these little creatures, their 

 curious structures, organization, and digestive apparatus, 

 are exhibited with perfect clearness, but that there is also 

 shewn the deep and brilliant colouring of their visual 

 organs, and the dehcate tints of their variable, retractile, 

 and locomotive processes. These living points — for the 

 space they individually occupy is hardly conceivable any 

 more than, taking the other extreme, and carrying our 

 views over the vast expanse of the starry heavens, we can 

 scarcely appreciate their magnitudes; and hence our 

 thoughts are alike directed upwards to a Being, whose com- 

 prehensiveness knows no limitation or bounds. In this 

 respect, the pursuit of the astronomer and the naturalist 

 may be said to be the same, for both travel very far, but 

 are ultimately lost in that infinity of purpose, to which 

 the human intellect cannot attain. What can be more 



