284 HISTORY OF 



by an ingenious countiyman of our own ; who asserts, that 

 these little animals, wliich thus appear swimming and sporting 

 lii almost every fluid we examine with a microscope, aie not 

 real living particles, but some of the more opaque parts of the 

 fluid that are thus increased in size, and seem to have a much 

 greater motion than they have in reality. For the motion being 

 magnified with the object, the smallest degree of it will seem 

 very considerable ; and a being almost at rest may, by these 

 means, be apparently put into violent action. Thus, for instance, 

 if we look upon the sails of a windmill moving at a distance, 

 they appear to go very slowj but, if we approach them, and thus 

 magnify their hullc to our eye, they go round with great rapidity. 

 A microscope, in the same manner, serves to bring our eye close 

 to the object, and thus to enlarge it ; and not only increase the 

 magnitude of its parts, but of its motion. Hence, therefore, it 

 would follow, that these organical particles, that are said to con- 

 stitute the bulk of living nature, are but mere optical illusions ; 

 and the system founded on them must, like them, be illusive. 



These, and many other objections, have been made to this 

 system ; which, instead of enlightening the mind, serve only to 

 show, that too close a pursuit of nature very often leads to un- 

 certainty. Happily, however, for mankind, the most intricate 

 inquiries are generally the most useless. Instead, therefore, of 

 b.'ilancing accounts between the sexes, and attempting to ascer- 

 tain to which the business of generation most properly belongs, 

 it will be more instructive, as well as amusing, to begin with 

 animal nature, from its earliest retirements, and evanescent out- 

 lines, and pursue the incipient creature through all its changes 

 in the womb, till it arrives into open day. 



The usual distinction of animals, with respect to their man- 

 ner of generation, has been into the oviparous and viviparous 

 kinds , or in other words, into those that bring forth an egg, 

 which is afterwards hatched into life, and those that bring forth 

 llieir young alive and perfect. In one of these two ways all ani- 

 mals were supposed to have been produced, and all other kinds 

 of generation were supposed imaginary or erroneous. But later 

 discoveries have taught us to be more cautious in making general 

 conclusions, and have even induced many to doubt whether 

 animal life may not be produced merely from putrefaction. ' 



1 Bonct Consid. p. 100. 



