33o OWEN'S POSITION IN 



since the establishment of the cell theory. 7 Its 

 importance as a factor in every theory of heredity 

 is obvious ; and it must have an equally im- 

 portant influence upon all theories of prolifera- 

 tion. But, for the present, I must express the 

 opinion that it affords very little more help 

 towards a scientific explanation of the phenomena 

 of ' Parthenogenesis ' than Owen's theory afforded 

 in the infancy of histological inquiry. Except by 

 the help of assumptions, of which there is no 

 proof, I do not see that modern speculation, at 

 present, gives us any better explanation why 

 the leaves of some plants prolify readily and 

 regularly, while those of others never do so ; or 

 why female cockroaches never exhibit sexless pro- 

 liferation while queen- bees always do so. The 

 ingenuity which fits hypotheses to facts by the 

 help of other hypotheses is always worthy of 

 admiration ; but, if it is to be useful, its purely 

 speculative character should never be lost sight 

 of. If science is to retain its strength, it must 

 keep in touch with the solid ground of observation. 

 In reading some of the biological literature of 

 the present day, I sometimes rub my eyes and 

 wonder whether I am not dreaming of the good 

 old days of the Naturphilosophfe. 



In the preceding pages I have endeavoured to 



7 I refer to the morpho- by this name ; not to any hypo- 

 logical generalisations known theses based upon them. 



