Il6 FOOT-NOTES TO EVOLUTION. 



conclusion they have shown that characters are ac- 

 quired, they have usually failed to show that they are 

 transmitted to descendants. Among animals one of the 

 best-known cases is the inheritance of 



irect epilepsy and other disorders in guinea- 

 experiment. 



pigs, due to certain nervous lesions of 



the parents. But Romanes,* who spent much time in 

 trying to corroborate these results, concludes as fol- 

 lows: "On the whole, then, as regards Brown-Sequard's 

 experiments, it will be seen that I have not been able to 

 furnish any approach to a full corroboration." 



Among plants, on the other hand, there is more and 

 better experimental evidence, but it is not by any means 

 as full or satisfactory as could be wished. Of one thing 

 we may be certain a satisfactory solution of the prob- 

 lem can be reached only 'by experiment. The mere 

 observations and inductions of the morphologist, while 

 affording valuable collateral evidence, can never furnish 

 the crucial test. As long as we deal merely with proba- 

 bilities of a low order there will be profound differences 

 of opinion e. g., Cope believes in all the Lamarckian 

 factors ; Romanes rejects use and disuse, but believes in 

 the others ; Weismann rejects all of them. Why ? Is 

 it because each does not know the facts upon which the 

 others build ? Certainly not. Those so-called facts are 

 merely probabilities of a higher or lower order, and to 

 one man they seem more important than to another. 

 No conviction based even upon a high degree of proba- 

 bility can ever be reached in this way. There is here 

 a deadlock of opinion, each challenging the other to 

 produce indubitable proof. This can never be furnished 

 by observation alone. Possibly even experiment may 

 fail in it, but at least it is the only hope. 



* G. J. Romanes. Post-Darwinian Questions, 1895. 



