IT. 



IT is hardly possible to write upon marine zoology 

 without either more or less alluding to those many 

 objects, invisible to the naked eye, which call for the 

 use of the microscope ; and it seems equally difficult 

 for any one who has been accustomed to this instru- 

 ment to speak in sober terms of its wonderful reve- 

 lations. The lines of Cowper, as the youngest student 

 in microscopic anatomy will readily acknowledge, 

 present no exaggerated picture of ecstasy : 



4 1 have seen a man, a worthy man, 

 In happy mood conversing with a fly; 

 And as he through his glass, made by himself, 

 Beheld its wondrous eye and plumage fine, 

 From leaping scarce he kept for perfect joy.* 



It is proper, however, to notice that a serious 

 objection has been urged against the use of the 

 microscope by young persons, namely, the injurious 

 effects of its habitual use upon the eyesight. 



So far as my experience goes, I cannot deny that 

 this objection is well founded. Since I have begun 

 to use the instrument, I am obliged, if I wish to 



