141 



by glasses. After thirty hours, we see tlie head, the 

 eyes, the heart, and the carina, with the vertebras 

 distinct. And by glasses we see all those parts, after 

 forty hours, which the naked eye cannot discern till 

 the fifth d^y. Whence it is probable, that even the 

 first discovery of them by the microscope, is not the 

 discovery of the parts newly formed, but of those that 

 existed before incubation, though not then dilated 

 enough to be visible. 



3. That there is a near analogy between animals 

 and plants. Now we know, the seeds of these are 

 only little plants, folded up in membranes. Hence we 

 may easily infer, that animals proceed from animal- 

 cula folded up, till they are gradually enlarged and un- 

 folded. 



And that these arrimalcula are originally in the seed 

 of the male, is probable. For 1. Numberless animal- 

 cula arc observed in the seed of animals. 2. We ob- 

 serve the rudiments of a fcetus in eggs fecundated by 

 the male, but not in others. 3. The rudiments in the 

 egg, both before and after incubation, exactly resem~ 

 ble the animalcula in the seed. 4. This gives a rational 

 account of many foetuses atone birth, especially that 

 of the Countess of Holland. It a-ccouots also for a 

 whole cluster of eggs in a hen, being fecundated at 

 once. 5. This best suits the analogy between animals 

 and plants. Every herb and tree bears its own seed ; 

 and a little plant of the same kind, which being thrown 

 into the womb of the earth, spreads forth its root and 

 receives its nourishment from the earth,but has its form 

 within itself* 



Yet, thaf no animal can be formed without the 

 egg of rfa female, is evinced by the following consi- 

 derations : 



1. No animalcula can come forward, if it do not 

 fall into a proper nidus. Sa though a thousand should 

 tail into one egg ? none of them would come forward^ 



