2/6 THE FOUNDATIONS OF ZOOLOGY 



wars, not only by the permission but by the command of the 

 Parliament, certain rapacious hands stripped not only my house 

 of its furniture, but what is subject for far greater regret with 

 me, my enemies abstracted from my museum the fruits of many 

 years of toil. 



"Whence it has come about that many observations, particularly 

 on the generation of insects, have perished, with detriment, I vent- 

 ure to think, to the republic of letters." 



These extracts seem to prove that, while it is easy to find in 

 his writings many passages in which belief in spontaneous gen- 

 eration is asserted, usually in the words of Aristotle, the validity 

 of these beliefs is admitted out of courtesy to Aristotle and for 

 the sake of the argument, as a subject on which he is not yet 

 prepared to make his researches public. 



If the reader who is interested will turn to the title-page of 

 the original edition of Harvey's Essay on Generation, he will note 

 that not only deer and human infants and serpents, but insects, as 

 well, are escaping from the bursting ^g^ which Jove holds in his 

 hand. 



As that practical old traveller, Herodotus, suggests that the 

 frogs and insects which are commonly supposed to be generated 

 out of the mud and slime of the Nile, may, perhaps, come from 

 eggs, Aristotle's readiness to believe in their spontaneous genera- 

 tion is hard to understand until we discover that the reason why 

 he saw nothing suspicious in the generation of animals from dead 

 and decomposing organic matter is to be found in his belief that 

 all generation takes place in the same way. 



Every conception, according to Aristotle, is a case of sponta- 

 neous generation out of excrement, and he regards the generation 

 of insects out of putrescent slime as a simple example, what 

 we should now call a primitive type, of generation in general, by 

 comparison with which more complicated and obscure cases are 

 to be interpreted. 



As a bloody substance is discharged at intervals from the 

 reproductive organs of the human female, he believed that the 

 mammalian embryo is generated out of this excrement, just as 

 other animals are generated out of decomposing matter of other 

 kinds. As heat causes milk to curdle, so he says the geniture of 



