The Microscope. 227 



tures are found, most of them invisible to the naked eye, and so 

 extremely minute, that many thousands of them will not cover the 

 space of a grain of sand; the httleness into which Nature descends 

 in these productions, nevertheless, offers one of the most agreea- 

 ble subjects for instruction and admiration; for by comparing one 

 of these minute living creatures with a larger animal, whose ap- 

 pearance is terrific, what a disproportion is observable, and what 

 efforts of the imagination does it not require to conceive the small- 

 ness of the parts of this minute Kving creature, for it will appear 

 they are furnished with as many or more members than the larg- 

 est animal,: they must have the means for the circulation of the 

 blood, a stomach for receiving their food and digesting it; — in a 

 word this little world contains objects, of the number and variety 

 of which we cannot have the smallest idea without the assistance 

 of the microscope. 



Class or Division of the Animalcula Infusaria. 



Those that have no External Organs. 1. Monas punctiforme; 

 a mere point. 2. Proteus mutabile; mutable or changeable. 3. 

 Volvox; spherical. 4. Enchehs cylindraceum; cylindrical 5. 

 Vibrio elongatum; long. 



JSIemhranaceous. 6. Cyclidium; oval. 7. Paramaecium; ob- 

 long. 8. Kolpoda; crooked. 9. Gonium; with angles. 10. Bur- 

 saria; hollow like a purse. 



Those that have External Organs. 11. Cercaria; with a tail. 

 12. Trichoda; hairy. 13. Kerona; horned. 14. Vorticella; the 

 apex ciliated. 



Equivocal or Spontaneous Generation. Equivocal or 

 spontaneous generation, that is, the production of plants without 

 seeds, and of living creatures without any other parents but acci- 

 dent and putrefaction; such was the absurd opinion that prevailed 

 of the production of the minute hving creatures, before the micro- 

 scope overturned it, by demonstrating that all plants have their 

 seeds, and all animals their eggs, whence the same species are 

 produced. Nothing seems more contrary to reason than to sup- 

 pose that chance should give being to regularity and beauty, or 

 that it should create living animals, fabricate a brain, nerves, and 

 all the parts of life; and, as Mr. Baker observes, we may as well 

 suppose that the woods generate stags and other animals that in- 

 habit them, as that a cheese generates mites without the egg. The 

 growth of animals and vegetables seems to be nothing more than 

 a gradual unfolding of their parts till they obtain their full size. 

 Though water, by merely standing a few days, will be found to 

 contain them, yet they will not be found in any degree so numer- 

 ous as when vegetable bodies have been steeped therein, for no 



