Darzi'in's Pan(jciicsis. 633 



enormous amount of literature which has since accumu- 

 lated on this subject, 1 and with regard to the older the- 

 ories, such as those of Spencer, Nageli and Ukrtwk;. 

 I need do no more than refer to my essay already quoted. 

 My only task is to show that the evidence, brought for- 

 ward in this book for the theory of mutati(jn, affords 

 a strong suport for the principle of pangenesis. All that 

 is necessary to bring the results of observation into line 

 with the doctrine of Pangenesis, is to substitute the idea 

 of internal factors or material vehicles of hereditarv 

 characters for the empirical units of the visible qual- 

 ities.^ This view has been best worked out by Johaxx- 

 sen in the section on the doctrine of pangenesis in his 

 textbook of botany wdiich has recently appeared ; and 

 this fact enables me to deal briefly with the topic.""' • 1 

 propose to confine myself to a brief exposition of Dak 

 win's conception of pangenesis and to the modification 

 of it which I suggested, without repeating all the obser- 

 vations on the subject which I have recorded in this borik. 

 I shall deal first with the essence of the hypothesis and 

 then with the secondary hypotheses; and shall defer a dis- 

 cussion of the essence of the theory until later. 



There are two essentially different views relatini,^ to 

 the material vehicles of the hereditary characters of or- 

 ganisms. One view is that of Spencer, according to 



^ Full lists of references are given in a large nnmlicr of wnrks 

 of which the following are among the best: C. Keller. I'crcrbun^s- 

 Ichre und Thiercucht. 1895; H. Marliere, Etudes sur riirrcditi'. iS«}5: 

 E. B. Wilson, The Cell in Development and Inheritance. \qoo\ I-ki-- 

 wiRTH, Die Ziichtung der landicirthseliaftlichen Culturf>fianceu, ujoi, 

 etc. 



""Ber. d. d. hot. Ges., tqoo. XVTTT. p. S3, -infl ^^tr les unites des 

 caracteres speciftqiics, Revue gcncralc de l)otani(iuc, 1900, XII. p. .257. 



'E. Warming and W. Johaknsen. Den alniindeli^e Pofnnik. 4th 

 ed., 1901, pp. 675 fif. It is quite satisfactory to state here that <f\ . rn' 

 critics of the first volume of my book have anticipated this conception 

 of the relation of the doctrine of mutation to pangenesis. 



