72 THE MICEOSCOPE.. 



THE MICEOSCOPE. The perfection to which the optical 

 and mechanical construction of the microscope has attained, 

 has conferred upon the naturalist an inestimable boon. 

 Every department of nature abounds with objects that cannot 

 be fully studied by the unaided eye alone, and thus magnify- 

 ing powers are necessary to unfold the intimate structure of 

 a large class of organic bodies ; a good microscope therefore 

 becomes indispensable to the geologist. This proposition is 

 proved by a brief statement of what its aid has effected in 

 palaeontology. Professor Owen observes "By the microscope 

 the supposed monarch of Saurian tribes, the so-called Basilo- 

 saurus has been deposed and removed from the head of the 

 reptilian to the bottom of the mammalian class. The 

 SaurocepTialus has been degraded from the class of reptiles to 

 that of fishes ; it has settled doubts entertained by some of 

 the highest authorities in palaeontology, as to the true 

 affinities of the gigantic megatherium, and by demonstrating 

 the identity of its dental structure with that of the Sloth, 

 has yielded us an unerring indication of the true nature of 

 its food." 



Important results have been obtained by the investigations 

 made by Messrs. Quekett and Bowerbank, on the intimate 

 structure of bone; from which it appears that the form, 

 size, and structure of the bone-cell alone is sufficient to 

 decide the class to which a doubtful specimen belongs. 

 The researches of these gentlemen will be referred to more 

 in detail in our chapter on palaeontology. 



Dr. Carpenter has shown that the microscopic structure 

 of shell affords important data for settling doubts upon the 

 affinities of certain families of the Mollusca ; and Dujardin 

 and D'Orbigny have more fully described by its. aid the sin- 

 gular and interesting group of shells known as Foramenifera, 

 which are so abundant in rocks of the cretaceous and ter- 

 tiary periods. Ehrenberg has shown that many deposits 

 in the tertiary series of Bohemia are composed of the silicious 

 shields of fossil infusoria; and the same fact has been observed 

 by the microscopists of our own country. 



This instrument is equally valuable to the investigator of 

 the remains of the earth's ancient Flora ; sections of the 

 vegetable structure assist the observer in deciding the 

 families to which the floras of successive periods belonged ; 



