158 LEISURE-TIME STUDIES. 



extended in their sphere from that which demonstrated the 

 origin of the maggots in meat soon turned the balance of 

 opinion in his favour. The inevitable tendency of the 

 human mind to "close with the truth" was thus exemplified, 

 and Redi's famous aphorism and motto, " Onme vivum ex 

 vivo" may be said to have formed the watchword of scientists 

 for many years after the recognition of his doctrines. It 

 has, however, been well remarked, that whilst Redi gave his 

 unhesitating and unqualified support to the idea that living 

 beings can originate only from pre-existing life, he admits, 

 in his works that he is unable to explain, according to this 

 theory, many cases of animal developments. For example, 

 when Redi discovered a caterpillar or grub in the heart of a 

 fruit, or buried within the familiar gall or excrescence grow- 

 ing on a tree, he appears to have had no idea of explaining 

 the origin of such insects from the outside world, that is, 

 from parent-insects, which punctured the bark of the tree, 

 depositing an egg in the puncture, and causing thereby the 

 gall to appear. The Florentine philosopher apparently pre- 

 ferred, in the absence of more definite knowledge, to credit 

 the plant itself with the production of the animal, and asserts 

 his belief that the galls and fruits are developed by the trees 

 as special provisions for the growth of the contained animal. 

 Even admitting this latter belief, however, it can hardly be 

 maintained that Redi meant thereby to illustrate a case of 

 spontaneous generation. Doubtless, he would have indig- 

 nantly denied any such assertion, and would have maintained 

 that the production of the insect in the gall or fruit as the 

 produce of a living tree, fully illustrated the aphorism that 

 life proceeds only from pre-existing life, in which statement, 

 as we have seen, his whole teaching was succinctly compre- 

 hended. 



After Redi's time, and until the middle of the eighteenth 

 century, the opinions he had advocated regarding the origin 

 of living beings, held their place as accredited maxims of 

 life-science. Probably the fact that these opinions were 

 thoroughly consistent with the visible order of nature, tended 



