I'jo Appendix. 



supporter of this side of the case from purely theoretical consid- 

 erations, for, although he concedes that, thus far there is no ab- 

 solute proof of the theory, he holds that the difficulties in the 

 way of ultimately establishing it are not only surmountable but 

 less formidable than those that face the supporters of Biogenesis. 



I may sum up then, without further detail, the whole matter, 

 by saying that there is no trustworthy evidence to-day that spon- 

 taneous generation has been demonstrated in a single instance. 

 Even Huxley, who declares that if it were given him '• to look 

 beyond the abyss of geologically recorded time to the still more re- 

 mote period when the earth was passing through physical and 

 chemical conditions which it can no more see again than a man 

 can recall his infancy, he should expect to be a witness of the 

 evolution of living protaplasm from not living matter" says very 

 significantly that, with this hmitation, Redi's great doctrine of 

 biogenesis seems to him victorious along the whole line at the 

 present day. Authority*, however, cannot settle the question, 



* Xotwithistanding this iidmission, I venture to add here a few opinions 

 wliicli I liave noted, without special search, in the course of my reading. 

 Even if not decisive of the question at issue, sucli opinions are interesting. 



Sir Wm. Thompson: "I am ready to adopt as an article of scientific faith, 

 true through all space and through all time, that life proceeds from life and 

 from nothing else." President's Address, Britisli Association, 1874. Nature, 

 Vol. IV, p. 269. 



Haeckel : "Positive contradiction of the hypothesis of Archigenesis is 

 impossible. Positive proof there is not yet since no one has yet seen any or- 

 ganism take origin except bj'' parentage. * * * Either the monera were 

 once for all at the beginning of organic life on the earth produced by Archi- 

 genesis, * * * * or in the course of the earth's history they have been pro- 

 duced by recurring acts of Archigenesis, and in this case there is no reason 

 why this process should not occur at the present time." Nature, March 2, 

 1.S71, p. •■!.■)«. 



J. BuRDON Sanderson: "I do not hold that spontaneous generation is 

 impossible. I do not regard heterogenists as scientific heretics. All I say is, 

 that up to the present moment I am not aware of any proof that they are 

 right." Nature, Oct. 2, 1873, p. 479. 



M. FIjOuuens: "So long as my opinion was not formed, I had nothing to 

 say. Now that it is formed I will express it. Pasteur's experiments are deci- 

 sive. If spontaneous generation is a reality what is necessary to produce ani- 

 malcules? Air and putrescible fluids. Now M. Pa,steur puts air and putres- 

 cibh' li<iuids togethurand nothing comes of it. There is then no spontaneous 



