24 MICROSCOPIC ILLUSTRATIONS. 



portion of us which furnishes all the endless variety of 

 objects from which we derive so great enjoyment 

 resembles, in its peculiar formation and arrangement, an 

 achromatic optical instrument. And if we descend to 

 the lower classes of animals nay, I would hardly say 

 lower, lest some perhaps might imagine that in their 

 small forms they do not evince as much perfection as is 

 discoverable in beings of a higher scale, and have not 

 all the functions which are necessary to life as full in 

 operation as even man himself if we enter upon an 

 investigation of their minute structures, we can deter- 

 mine absolutely nothing without the microscope ; and 

 our knowledge of the very existence of many highly- 

 organized and active creatures is wholly dependent 

 upon it. 



Vegetable organography, upon which the modern 

 botanist depends so much for his systematic arrangement, 

 and with which the student is so greatly interested and 

 amused, owes almost its very existence to the microscope. 

 This observation will be found to apply in an especial 

 manner both to the cellular and vascular tissues of plants. 

 The membranous cellules of cellular tissue are some- 

 times not more than 1- 1000th of an inch in diameter; 

 and those of the ordinary size are about 1 -200th or 

 l-300th. How, then, is it possible that we could become 

 acquainted with their forms and arrangement but by the 

 aid of the microscope? And so with respect to vascular 

 tissue : it is absolutely indispensable toward acquiring- 

 an accurate knowledge of the structure and forms of 



