MICROSCOPES. 253 



Equivocal or Spontaneous Generation. Equivocal or spon- 

 taneous, generation, that is, the production of plants without 

 seeds, and of living creatures without any other parents but 

 accident and putrefaction ; such was the absurd opinion that 

 prevailed of the production of the minute living creatures, 

 before the microscope 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 suppose 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 inhabit 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 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 numerous as when vegetable bodies have been 

 steeped therein, for no living creatures seem to subsist upon 

 water alone ; but when it is stored with their proper food, 

 myriads may be found in every drop, of the greatest variety 

 in their forms : some are round, some oblong, and others 

 spherical, and the greatest part of them transparent : mo- 

 tion seems to be their greatest delight ; they pervade with 

 ease and the greatest rapidity the whole dimensions of the 

 drop of water, in which they find ample space ; sometimes 

 they dart forwards, and at others more obliquely; then 

 again in a circle, and though hundreds may be seen in a 

 single drop, yet they never strike against one another. They 

 differ in their size ; some are barely visible to the eye ; some 

 so minute as to resist the action of the microscope, and ap- 

 pear only as moving points ; of this description is the mo- 

 nus ; it is so extremely delicate and transparent, as some- 

 times to elude the highest magnifying power : some are, no 

 doubt, inhabitants of the water, and others turn into small 

 flies, and deposit their eggs in any kind of fluid producing 

 proper nourishment for their young ; the eggs being hatched, 

 they live a certain time in this element, then take wing after 

 a complete change in their forms. This may often be ob- 

 served, for when they grow to a certain size, of a sudden 

 you will find them gone, and a small race supply their place. 

 As these infusions, to produce them, are all prepared in a 

 VOL. ii. 22 



