of Heredity 35 



To these as yet altogether unconformable cases we can 

 scarcely doubt that further experiment will add many more. 

 Indeed we already have tolerably clear evidence that many 

 phenomena of inheritance are of a much higher order of 

 complexity. When the paper on Pisum was written 

 Mendel apparently inclined to the view that with modi- 

 fications his law might be found to include all the phenomena 

 of hybridisation, but in the brief subsequent paper on 

 Hieracium he clearly recognized the existence of cases of 

 a different nature. Those who read that contribution will 

 be interested to see that he lays down a principle which 

 may be extended from hybridisation to heredity in general, 

 that the laws of each new case must be determined by 

 separate experiment. 



As regards the Mendelian principles, which it is the 

 chief aim of this introduction to present clearly before the 

 reader, a professed student of variation will easily be able 

 to fill in the outline now indicated, and to illustrate the 

 various conceptions from phenomena already familiar. To 

 do this is beyond the scope of this short sketch. But 

 enough perhaps has now been said to show that by the 

 application of those principles we are enabled to reach and 

 deal in a comprehensive manner with phenomena of a 

 fundamental nature, lying at the very root of all con- 

 ceptions not merely of the physiology of reproduction 

 and heredity, but even of the essential nature of living 

 organisms ; and I think that I used no extravagant words 

 when, in introducing Mendel's work to the notice of readers 

 of the Royal Horticultural Society's Journal, I ventured to 

 declare that his experiments are worthy to rank with those 

 which laid the foundation of the Atomic laws of Chemistry. 



32 



