54 DROPS OF WATEE. 



that of describing the objects I select in regular 

 succession, according to Ehrenberg's classifica- 

 tion, with the exception of the family Bacittaria, 

 which I place first, as the species are now consi- 

 dered (at least, the greater part of them) to belong 

 to the vegetable kingdom. I shall suppose four 

 DROPS OF WATER to be under inspection at diffe- 

 rent times ; and though it seldom happens that 

 the objects I have depicted in each drop are found 

 alone at any period, still I have thought this plan 

 not an unnatural one, giving clearly some idea of 

 classification, and preparing the way for more 

 scientific works, when the subject is made a deeper 

 study. The specimens contained in the First Drop 

 are minute Algae, and other objects nearly allied 

 to them : they are found more particularly in 



