5 8 OMNE VIVUM EX OVO. 



organisms by division and subdivision, which has 

 been observed and confirmed in many cases by 

 hundreds of competent observers. Nothing is gained 

 by the statement being repeated over and over again 

 that lifeless particles of matter come together and 

 form a living thing, save that by mere iteration 

 people who have concerned themselves little with the 

 subject may be persuaded to assent to the view advo- 

 cated. But knowledge cannot be advanced by de- 

 clarations and affirmations, or by the consent of 

 numbers. 



Very recently this question of spontaneous generation 

 has been re-opened in this country, by Dr. Bastian, 

 whose papers will be found in "Nature," for June 3<Dth, 

 July /th and I4th, 1870. New experiments have 

 been made, and the author comes forward as a warm 

 advocate of the doctrine of Heterogenesis. He com- 

 mences, however, by adducing arguments in favour of 

 the view which he seeks to establish. These argu- 

 ments are founded upon evidence which we possessed 

 before he commenced his experiments. He endeavours 

 in the first instance to convince the reader that proba- 

 bilities are strongly in favour of heterogenesis, in order 

 to prepare him for the acceptance of the conclusions 

 he has himself deduced from his experiments. 



But it is obvious that if already existing evidence 

 were really as decisive in favour of the doctrine as the 

 reader is led to suppose it to be, new experiments 

 were unnecessary and superfluous, while if, on the 



