THOUGHTS ON ANIMALCULES. x 



To an intelligent person, who has previously obtained 

 a general idea of the nature of the objects about to be 

 submitted to his inspection, a group of living animal- 

 cules, seen under a powerful microscope for the first 

 time, presents a scene of extraordinary interest, and 

 never fails to call forth an expression of amazement and 

 admiration*. This statement admits of an easy illus- 



* It is so absolutely necessary that the observer should previously have 

 a general notion of the objects to be inspected, that I solicit the reader's 

 attention to the following pertinent remarks of Captain Basil Hall. " I 

 have known many observant and quick- sighted men fail to perceive a 

 double star in the heavens, while to others more practised, though using 

 the same telescope, both objects were clearly denned. The secret often 

 lies in knowing exactly what to look for, and thence learning how to ad- 

 just, not merely the focus of the eye, but what may be termed the focus 

 of the judgment, so as to be able to pitch the understanding into such a 

 key that the information may be understood when it comes. I remember 

 being present once at the Geological Society, when a bottle was produced, 

 which was said to contain certain zoophytes. It was handed round, in 

 the first instance, among the initiated on the foremost benches, who com- 

 mented freely with one another on the forms of the animals in the fluid ; 

 but, when it came to our hands, we could discover nothing in the bottle 

 but the most limpid fluid, without any trace, so far as our optics could 

 make out, of animals dead or alive, the whole appearing absolutely trans- 

 parent. The surprise of the ignorant at seeing nothing was only equal 

 to that of the learned who saw so much to admire ; nor was it till we were 

 specifically instructed what we were to look for, and the shape, size, and 

 general aspect of the zoophytes pointed out, that our understandings 

 began to co-operate with our eyesight in peopling the fluid, which, up to 

 that moment, had seemed perfectly uninhabited. The wonder then was, 

 how we could possibly have omitted seeing objects now so palpable." 



